Ink-jet recording ink and method of ink-jet recording

ABSTRACT

An inkjet recording ink comprising an aqueous medium having dissolved and/or dispersed therein a phthalocyanine dye, wherein the phthalocyanine dye is a water-soluble dye having an oxidation potential more positive than 1.0 V (vs SCE) and the ink comprises a water-miscible organic solvent having a vapor pressure of 2,000 Pa or less at  20 ° C.; and an inkjet recording method using the ink. By virtue of such a constitution, an inkjet recording ink and an inkjet recording method are provided, which can ensure high ejection stability, good color hue of the obtained image, no drying of the ink at the inkjet head, excellent fastness to light and water, image quality free from defective such as fineline blurring under high-humidity condition, and good preservability of the image under severe conditions, and furthermore can ensure high storability and high ejection stability even after aging for a long time or under severe conditions.

TECHNICAL FIELD

The present invention relates to an inkjet recording ink capable ofproviding a high-quality recorded image, exhibiting excellent ejectiondurability even after long-term aging of the ink solution and ensuringexcellent preservability of the obtained image under high-humiditycondition, and also relates to an inkjet recording method using the ink.

BACKGROUND ART

Accompanying recent popularization of computers, an inkjet printer iswidely used for printing letters or drawing an image on paper, film,cloth or the like not only at offices but also at homes.

The inkjet recording method includes a system of jetting out a liquiddroplet by applying a pressure from a piezoelectric element, a system ofjetting out a liquid droplet by generating a bubble in the ink underheat, a system of using an ultrasonic wave, and a system of jetting outa liquid droplet by suction using an electrostatic force. The ink usedfor such inkjet recording includes an aqueous ink, an oily ink and asolid (fusion-type) ink. Among these inks, an aqueous ink ispredominating in view of production, handleability, odor, safety and thelike.

The dye used in such an inkjet recording ink is required to have highsolubility in a solvent, enable high-density recording, provide goodcolor hue, exhibit excellent fastness to light, heat, air, water andchemicals, ensure good fixing to an image-receiving material and lessbleeding, give an ink having excellent storability, have high purity andno toxicity, and be available at a low cost.

However, it is very difficult to find out a dye satisfying theserequirements in a high level. In particular, a dye having good cyancolor hue and excellent weather-resistant fastness is being keenlydemanded.

Various dyes and pigments for inkjet recording have been alreadyproposed and are actually used, but a dye satisfying all of therequirements is not yet found out at present. Conventionally well-knowndyes and pigments having a color index (C.I.) number can hardly satisfyboth color hue and fastness required of the ink for inkjet recording. Asfor the dye capable of improving the fastness, azo dyes derived from anaromatic amine and a heterocyclic 5-membered ring amine have beenproposed in JP-A-55-161856 (the term “JP-A” as used herein means an“unexamined published Japanese patent application”). However, these dyeshave a problem of bad color reproducibility due to undesirable color huepresent in the yellow and cyan regions. JP-A-61-36362 and JP-A-2-212566are disclosing an inkjet recording ink with an attempt to satisfy bothcolor hue and light fastness. However, in use as a water-soluble ink,the dyes used in these patent publications are insufficient in thesolubility in water. Also, when the dyes described in these patentpublications are used as a water-soluble ink for inkjet recording, therearises a problem in the fastness to humidity and heat. In order to solvethese problems, compounds and inks described in JP-T-11-504958 (the term“JP-T” as used herein means a “published Japanese translation of a PCTpatent application”) have been proposed. Furthermore, an inkjetrecording ink using a pyrazolylaniline azo dye for improving the colorhue and light fastness is described (see, Japanese Patent ApplicationNo. 2000-80733). However, these inkjet recording inks all areinsufficient in the color reproducibility and fastness of the imageoutput.

It has been also found that when an image is recorded on an inkjetspecial glossy paper for photographic image quality and put on a wall ina room, the image preservability is sometimes extremely bad. The presentinventors assume that this phenomenon is ascribable to some oxidativegas in air, such as ozone. This phenomenon does not occur when the airflow is shut out, for example, by putting the image in a glass-madeframe.

This phenomenon is outstanding particularly in the case of inkjetspecial glossy paper for photographic image quality and is a largeproblem for current inkjet recording systems where one of importantcharacteristics is the photographic image quality.

Also, as described above, in preparing an ink solution, when only wateris used, the penetrability into a medium is bad and the image is notfixed in many cases. In addition, the liquid properties necessary forhitting as an ink are often not satisfied. For solving these problems, atechnique of using a water-miscible organic solvent as an auxiliarysolvent is commonly employed in this field. However, mere use of awater-miscible organic solvent has been found to cause a problem thatthe image formed is readily blurred under high-humidity condition or theejection stability is impaired due to drying of the ink at the inkjethead.

Accordingly, an object of the present invention is to provide an inkjetrecording ink which is an aqueous ink in view of handleability, odor,safety and the like and which can ensure high ejection stability, goodcolor hue of the obtained image, no drying of the ink at the inkjethead, excellent fastness to light and water, image quality free fromdefective such as fineline blurring under high-humidity condition, andgood preservability of the image under severe conditions. Another objectof the present invention is to provide an ink set capable of ensuringhigh storability and high ejection stability even after aging of the inkfor a long time or under severe conditions.

DISCLOSURE OF THE INVENTION

The characteristic feature of the inkjet recording ink of the presentinvention is that an inkjet recording ink comprising an aqueous mediumdissolved or dispersed therein a specific phthalocyanine dye describedbelow contains a water-miscible organic solvent having a vapor pressureof 2,000 Pa or less at 20° C.

The characteristic feature of the method for producing an inkjetrecording ink of the present invention is that the method for producingan inkjet recording ink comprises at least a step of adding sonicvibration and/or that in the method of producing an inkjet recordingink, the inkjet recording ink solution prepared is filtered through afilter having an effective pore diameter of 1 μm or less, defoamed andthen used.

The above-described objects of the present invention can be attained bythe following preferred techniques.

1. An inkjet recording ink comprising an aqueous medium dissolved ordispersed therein a phthalocyanine dye, wherein said phthalocyanine dyeis a water-soluble dye having an oxidation potential more positive than1.0 V (vs SCE) and the ink comprises a water-miscible organic solventhaving a vapor pressure of 2,000 Pa or less at 20° C.

2. The inkjet recording ink as described in 1, which comprises at leastone organic solvent having a boiling point of 150° C. or more as thewater-miscible organic solvent.

3. The inkjet recording ink as described in 2, wherein the at least oneorganic solvent having a boiling point of 150° C. or more is an alcoholderivative.

4. The inkjet recording ink as described in 1, which comprises at leastone organic solvent having a boiling point of less than 150° C. as thewater-miscible organic solvent.

5. The inkjet recording ink as described in 4, wherein the at least oneorganic solvent having a boiling point of less than 150° C. is analcohol derivative.

6. The inkjet recording ink as described in 1, which comprises apolyhydric alcohol and/or a derivative thereof as the water-miscibleorganic solvent.

7. The inkjet recording ink as described in 6, which comprises a mixtureof two or more members containing the polyhydric alcohol and/or aderivative thereof.

8. The inkjet recording ink as described in 6 or 7, which comprises thepolyhydric alcohol and/or a derivative thereof at a concentration of 10to 60 (mass/volume) %.

9. The inkjet recording ink as described in 1, which comprises anorganic solvent, in which the phthalocyanine dye has a solubility of 10(g/100 g-solvent) or more at 25° C., as the water-miscible organicsolvent.

10. The inkjet recording ink as described in 9, which comprises awater-miscible organic solvent, in which the phthalocyanine dye has asolubility of 10 (g/100 g-solvent) or more at 25° C., in an amount of 10mass % or less in the ink.

11. The inkjet recording ink as described in 1, which comprises anorganic solvent, which is liquid at ordinary temperature and does notcontain a heteroatom other than an oxygen atom, as the water-miscibleorganic solvent.

12. The inkjet recording ink as described in 11, wherein the organicsolvent has a boiling point of 150° C. or more.

13. The inkjet recording ink as described in 11 or 12, wherein theorganic solvent is an alcohol derivative and is selected from a monool,a diol and a triol.

14. The inkjet recording ink as described in 1, wherein the watercontent is from 40 to 80 mass % based on the ink solution.

15. The inkjet recording ink as described in any one of 1 to 14, whereinwhen the monochromatic moiety printed by using a single (cyan) color ofthe ink so as to give a cyan reflection density of 0.9 to 1.1 in aStatus A filter is stored in an ozone environment of 5 ppm for 24 hours,a dye residual ratio (density after color fading/initial density×100) is60% (preferably 80%) or more.

16. The inkjet recording ink as described in any one of 1 to 15, whereinafter color fading with ozone under the conditions of claim 15, theamount of Cu ion flowed out into water is 20% or less of all dyes.

17. The inkjet recording ink as described in any one of 1 to 16, whereinthe phthalocyanine dye is a water-soluble dye having anelectron-withdrawing group at the β-position of a benzene ring of saidphthalocyanine.

18. The inkjet recording ink as described in any one of 1 to 17, whereinsaid phthalocyanine dye is a water-soluble phthalocyanine dye producedby a process not passing through sulfonation of an unsubstitutedphthalocyanine.

19. The inkjet recording ink as described in 1 to 18, wherein saidphthalocyanine dye is represented by the following formula (I):

wherein X₁, X₂, X₃ and X₄ each independently represents —SO-Z, —SO₂-Z,—SO₂NR1R2, a sulfo group, —CONR1R2 or —CO₂R1;

Z represents a substituted or unsubstituted alkyl group, a substitutedor unsubstituted cycloalkyl group, a substituted or unsubstitutedalkenyl group, a substituted or unsubstituted aralkyl group, asubstituted or unsubstituted aryl group, or a substituted orunsubstituted heterocyclic group, and R1 and R2 each independentlyrepresents a hydrogen atom, a substituted or unsubstituted alkyl group,a substituted or unsubstituted cycloalkyl group, a substituted orunsubstituted alkenyl group, a substituted or unsubstituted aralkylgroup, a substituted or unsubstituted aryl group, or a substituted orunsubstituted heterocyclic group, provided that when a plurality of Zsare present, these may be the same or different,

Y₁, Y₂, Y₃ and Y₄ each independently represents a monovalentsubstituent,

provided that when a plurality of X₁s, X₂s, X₃s, X₄s, Y₁s, Y₂s, Y₃s orY₄s are present, these may be the same or different,

a₁ to a₄ and b₁ to b₄ represent the number of substituents X₁ to X₄ andY₁ to Y₄, respectively, a₁ to a₄ each independently represents aninteger of 0 to 4 but all are not 0 at the same time, b₁ to b₄ eachindependently represents an integer of 0 to 4, and

M represents a hydrogen atom, a metal atom or an oxide, hydroxide orhalide thereof.

20. The inkjet recording ink as described in 19, wherein the dyerepresented by formula (I) is a dye represented by the following formula(II):

wherein X₁₁ to X₁₄, Y₁₁ to Y₁₈ and M₁ have the same meanings as X₁ toX₄, Y₁ to Y₄ and M in formula (I), respectively, and

a₁₁ to a₁₄ each independently represents an integer of 1 or 2.

21. An inkjet recording method comprising using the inkjet recording inkdescribed in 1 to 20.

22. An inkjet recording method comprising ejecting ink dropletsaccording to recording signals on an image-receiving material comprisinga support having thereon an image-receiving layer containing a whiteinorganic pigment particle, thereby recording an image on theimage-receiving material, wherein said ink droplet comprises the inkjetrecording ink described in 1 to 20.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in detail below.

As a result of intensive investigations on the inkjet recording ink, thepresent inventors have found that the properties required of the dyeare 1) to give a good color hue and be free of change in the color hue(chromism of solvate), 2) to exhibit excellent fastness (to light,ozone, NOx, solvent, oil and water), 3) to be safe (not carcinogenic byAMES, not irritating to skin and easily degradable), 4) to beinexpensive, 5) to have high ε, 6) to be highly soluble, and 7) to havestrong fixing property to a medium.

The properties required of the ink and conc. ink are 1) to be uniformirrespective of the temperature and aging, 2) to be less contaminated,3) to exhibit good penetration into a medium, 4) to be uniform in thehitting size, 5) to be usable for all types of paper, 6) to be easilyprepared, 7) to ensure no ejection error, less bubbling and easydefoaming, and 8) to be stably ejected.

The properties required of the image is 1) to be clear without blurring,discoloration and beading, 2) to have scratch resistance, 3) to havehigh and uniform gloss, 4) to have good image preservability andexcellent balance in color fading, 5) to be quickly dried, 6) to beprinted at a high speed, and 7) to have no image density dependency inthe color fading ratio.

The properties required of the inkjet recording ink is to be excellentin both light fastness and ozone resistance and small in the change ofcolor hue and surface state (less generation of bronze and lessprecipitation of dye). As for the light fastness (OD1.0), the lightfastness with a TAC filter on Epson PM Photographic Image-ReceivingPaper by Xe of 1.1 W/m (intermittent conditions) is preferably 90% ormore in terms of the residual color ratio for 3 days. Also, the dyeresidual ratio for 14 days is preferably 85% or more. As for the ozoneresistance, the ozone resistance (OD1.0) under the condition of 5 ppm orless of ozone is preferably 60% or more, more preferably 70% or more,still more preferably 80% or more, in terms of the dye residual ratiofor one day. Also, the dye residual ratio for 5 days is preferably 25%or more, more preferably 40% or more, still more preferably 50% or more.Samples varied in the coated amount of the dye are prepared by GTC andthe amount of Cu element contained in the dye is measured by afluorescent X ray.

The Cu ion is present in the form of a phthalate as a result ofdecomposition of a phthalocyanine dye. The amount of the Cu salt presentin an actual print is preferably 10 mg/m² or less in terms of Cu ion.The amount of Cu flowed out from the print is determined by forming anentire cyan solid image having a Cu salt amount of 20 mg/m² or less interms of Cu ion, color-fading this image with ozone and analyzing theamount of ion flowed out into water. Incidentally, all Cu compounds aretrapped by the image-receiving material before the color fading. Theamount of Cu ion flowed out into water is preferably 20% or less of alldyes.

It has been found by the present invention that a phthalocyanine dyehaving such properties can be obtained, for example, by 1) elevating theoxidation potential, 2) enhancing the aggregation property, 3)introducing an aggregation accelerating group, intensifying the hydrogenbond at the time of π-π stacking, or 4) not incorporating a substituentat the α-position, that is, facilitating the stacking.

Conventional phthalocyanine dyes used for the inkjet ink are derivedfrom an unsubstituted phthalocyanine through sulfonation and these are amixture which cannot be specified in the number and positions ofsubstituents. On the other hand, the dye for use in the inkjet recordingink of the present invention is a phthalocyanine dye which can bespecified in the number and positions of substituents. The firststructural feature is that the dye is a water-soluble phthalocyanine dyeobtained by not passing through sulfonation of an unsubstitutedphthalocyanine. The second structural feature is that the dye has anelectron-withdrawing group at the β-position of a benzene ring ofphthalocyanine, preferably at the β-position of all benzene rings.Specific examples of useful dyes include those where a sulfonyl group issubstituted (see, Japanese Patent Application Nos. 2001-47013 and2001-190214), a sulfamoyl group in general is substituted (see, JapanesePatent Application Nos. 2001-24352 and 2001-189982), a heterocyclicsulfamoyl group is substituted (see, Japanese Patent Application Nos.2001-96610 and 3001-190216), a heterocyclic sulfonyl group issubstituted (see, Japanese Patent Application Nos. 2001-76689 and2001-190215), a specific sulfamoyl group is substituted (see, JapanesePatent Application No. 2001-57063), a carbonyl group is substituted(see, Japanese Patent Application No. 2002-012869), or a specificsubstituent for enhancing the solubility or ink stability or preventingthe bronze phenomenon, such as asymmetric carbon (see, Japanese PatentApplication No. 2002-012868) or Li salt (see, Japanese PatentApplication No. 2002-012864), is substituted.

The first physical feature of the dye for use in the inkjet recordingink of the present invention is to have a high oxidation potential. Theoxidation potential is preferably more positive than 1.00 V, morepreferably more positive than 1.1 V, and most preferably more positivethan 1.2 V. The second physical feature is to have a strong aggregationproperty. Specific examples of the dye having this property includethose where the aggregation of oil-soluble dyes is specified (see,Japanese Patent Application No. 2001-64413) or the aggregation ofwater-soluble dyes is specified (see, Japanese Patent Application No.2001-117350).

With respect to the relationship between the number of aggregatinggroups and the performance (light absorbance of ink), when anaggregating group is introduced, reduction of light absorbance orshifting of λmax to the shorter wave is liable to occur even in a dilutesolution. With respect to the relationship between the number ofaggregating groups and the performance (reflection OD on Epson PM920Image-Receiving Paper), as the number of aggregating groups increases,the reflection OD at the same ion intensity more decreases. That is, theaggregation is considered to proceed on the image-receiving paper. Withrespect to the relationship between the number of aggregating groups andthe performance (ozone resistance/light fastness), as the number ofaggregating groups increases, the ozone resistance is more enhanced. Adye having a large number of aggregating groups tends to be enhancedalso in the light fastness. In order to impart the ozone resistance, theabove-described substituent X (which represents X₁, X₂, X₃, X₄ or thelike) must be present. The reflection OD and the fastness are in thetrade-off relationship and therefore, it is necessary to enhance thelight fastness without weakening the aggregation.

Preferred embodiments of the ink of the present invention are:

1) a cyan ink where the light fastness with a TAC filter on Epson PMPhotographic Image-Receiving Paper by Xe of 1.1 W/m (intermittentconditions) is 90% or more in terms of the residual color ratio for 3days;

2) a cyan ink where after storage in an ozone environment of 5 ppm for24 hours, the monochromatic moiety printed by using a single (cyan)color of the ink to give a cyan reflection density of 0.9 to 1.1 in aStatus A filter has a dye residual ratio (density after colorfading/initial density×100) of 60% (preferably 80%) or more;

3) a cyan ink where after color fading with ozone under the conditionsof 2 above, the amount of Cu ion flowed out into water is 20% or less ofall dyes; and

4) a cyan ink having penetrability such that the amount of inkpenetrated into a specific image-receiving paper is 30% or more of theupper portion of the image-receiving layer.

The dye contained in the inkjet recording ink of the present inventionis a phthalocyanine dye, preferably a water-soluble dye having anoxidation potential more positive than 1.0, more preferably a dye havingozone gas fastness satisfying the above-described conditions, still morepreferably a phthalocyanine dye represented by formula (I).

The phthalocyanine dye is a dye having fastness but this dye is known tobe inferior in the fastness to ozone gas when used as a dye for inkjetrecording.

In the present invention, an electron-withdrawing group is preferablyintroduced into the phthalocyanine skeleton to render the oxidationpotential more positive than 1.0 V (vs SCE) and thereby reduce thereactivity with ozone which is an electrophilic agent. A more positiveoxidation potential is more preferred and the oxidation potential ismore preferably more positive than 1.1 V (vs SCE) and most preferablymore positive than 1.2 V (vs SCE).

The oxidation potential value (Eox) can be easily measured by oneskilled in the art and the method therefor is described, for example, inP. Delahay, New Instrumental Methods in Electrochemistry, IntersciencePublishers (1954), A. J. Bard et al., Electrochemical Methods, JohnWiley & Sons (1980), and Akira Fujishima et al., Denkikagaku Sokutei Ho(Electrochemical Measuring Method), Gihodo Shuppan Sha (1984).

More specifically, a test sample is dissolved to a concentration of1×10⁻⁴ to 1×10⁻⁶ mol/liter in a solvent such as dimethylformamide oracetonitrile containing a supporting electrolyte such as sodiumperchlorate or tetrapropylammonium perchlorate and the oxidationpotential is measured as a value to SCE (saturated calomel electrode) byusing a cyclic voltammetry or a direct current polarography. This valuesometimes deviates on the order of tens of millivolt due to the effectof, for example, liquid junction potential or liquid resistance ofsample solution, but the reproducibility of potential can be guaranteedby adding a standard sample (for example, hydroquinone).

In order to univocally specify the potential, in the present invention,the value (vs SCE) measured by a direct current polarography in adimethylformamide (concentration of dye: 0.001 mol dm⁻³) containing 0.1mol dm⁻³ of tetrapropylammonium perchlorate as the supportingelectrolyte is used as the oxidation potential of the dye.

The Eox (oxidation potential) value indicates the transferability of anelectron from the sample to the electrode and as the value is larger(the oxidation potential is more positive), the electron is lesstransferable from the sample to the electrode, in other words, theoxidation less occurs. As for the relationship with the structure ofcompound, the oxidation potential becomes more positive when anelectron-withdrawing group is introduced, and becomes more negative whenan electron-donating group is introduced. In the present invention, theoxidation potential is preferably rendered more positive by introducingan electron-withdrawing group into the phthalocyanine skeleton so as toreduce the reactivity with ozone which is an electrophilic agent. Whenthe Hammett's substituent constant σp value as a measure for theelectron-withdrawing property or electron-donating property ofsubstituent is used, the oxidation potential can be rendered morepositive by introducing a substituent having a large up value, such assulfinyl group, sulfonyl group and sulfamoyl group.

Also for the purpose of such potential control, the phthalocyanine dyerepresented by formula (I) is preferably used.

The phthalocyanine dye having the above-described oxidation potential isapparently a cyanine dye excellent in both the light fastness and theozone resistance, because this dye satisfies those conditions for lightfastness and ozone resistance.

The phthalocyanine dye (preferably the phthalocyanine dye represented byformula (I)) for use in the present invention is described in detailbelow.

In formula (I), X₁, X₂, X₃ and X₄ each independently represents —SO-Z,—SO₂-Z, —SO₂NR1R2, a sulfo group, —CONR1R2 or —CO₂R1. Among thesesubstituents, preferred are —SO-Z, —SO₂-Z, —SO₂NR1R2 and —CONR1R2, morepreferred are —SO₂-Z and —SO₂NR1R2, and most preferred is —SO₂-Z. In thecase where a₁ to a₄ showing the number of substituents each represents anumber of 2 or more, a plurality of substituents X₁, X₂, X₃ or X₄ may bethe same or different and each independently represents any one of theabove-described groups. X₁, X₂, X₃ and X₄ may be completely the samesubstituents, may be substituents of the same kind but partiallydifferent as in the case, for example, where X₁, X₂, X₃ and X₄ all are—SO₂-Z and Zs are different from each other, or may include substituentsdiffering from each other, for example, —SO₂-Z and —SO₂NR1R2.

Each Z independently represents a substituted or unsubstituted alkylgroup, a substituted or unsubstituted cycloalkyl group, a substituted orunsubstituted alkenyl group, a substituted or unsubstituted aralkylgroup, a substituted or unsubstituted aryl group, or a substituted orunsubstituted heterocyclic group, preferably a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group ora substituted or unsubstituted heterocyclic group, and most preferably asubstituted alkyl group, a substituted aryl group or a substitutedheterocyclic group.

R1 and R2 each independently represents a hydrogen atom, a substitutedor unsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted alkenyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,or a substituted or unsubstituted heterocyclic group, preferably ahydrogen atom, a substituted or unsubstituted alkyl group, a substitutedor unsubstituted aryl group, or a substituted or unsubstitutedheterocyclic group, more preferably a hydrogen atom, a substituted alkylgroup, a substituted aryl group or a substituted heterocyclic group.However, it is not preferred that R1 and R2 both are a hydrogen atom.

The substituted or unsubstituted alkyl group represented by R1, R2 and Zis preferably an alkyl group having from 1 to 30 carbon atoms, morepreferably a branched alkyl group because the solubility of dye and thestability of ink are improved, still more preferably an alkyl grouphaving an asymmetric carbon (use in the racemic form). Examples of thesubstituent include those described later as the substituent when Z, R1,R2, Y₁, Y₂, Y₃ and Y₄ can further have a substituent. In particular, ahydroxyl group, an ether group, an ester group, a cyano group, an amidogroup and a sulfonamido group are preferred because the aggregatingproperty and fastness of dye are enhanced. Other than these, the alkylgroup may be substituted by a halogen atom or an ionic hydrophilicgroup. Incidentally, the number of carbon atoms in the alkyl group doesnot contain carbon atoms of substituents and this applies to othergroups.

The substituted or unsubstituted cycloalkyl group represented by R1, R2and Z is preferably a cycloalkyl group having from 5 to 30 carbon atoms,more preferably a cycloalkyl group having an asymmetric carbon (use inthe racemic form) because the solubility of dye and the stability of inkare improved. Examples of the substituent include those described lateras the substituent when Z, R1, R2, Y₁, Y₂, Y₃ and Y₄ can further have asubstituent. In particular, a hydroxyl group, an ether group, an estergroup, a cyano group, an amido group and a sulfonamido group arepreferred because the aggregating property and fastness of dye areenhanced. Other than these, the cycloalkyl group may be substituted by ahalogen atom or an ionic hydrophilic group.

The substituted or unsubstituted alkenyl group represented by R1, R2 andZ is preferably an alkenyl group having from 2 to 30 carbon atoms, morepreferably a branched alkenyl group because the solubility of dye andthe stability of ink are improved, still more preferably an alkenylgroup having an asymmetric carbon (use in the racemic form). Examples ofthe substituent include those described later as the substituent when Z,R1, R2, Y₁, Y₂, Y₃ and Y₄ can further have a substituent. In particular,a hydroxyl group, an ether group, an ester group, a cyano group, anamido group and a sulfonamido group are preferred because theaggregating property and fastness of dye are enhanced. Other than these,the alkenyl group may be substituted by a halogen atom or an ionichydrophilic group.

The substituted or unsubstituted aralkyl group represented by R1, R2 andZ is preferably an aralkyl group having from 7 to 30 carbon atoms, morepreferably a branched aralkyl group because the solubility of dye andthe stability of ink are improved, still more preferably an aralkylgroup having an asymmetric carbon (use in the racemic form). Examples ofthe substituent include those described later as the substituent when Z,R1, R2, Y₁, Y₂, Y₃ and Y₄ can further have a substituent. In particular,a hydroxyl group, an ether group, an ester group, a cyano group, anamido group and a sulfonamido group are preferred because theaggregating property and fastness of dye are enhanced. Other than these,the aralkyl group may be substituted by a halogen atom or an ionichydrophilic group.

The substituted or unsubstituted aryl group represented by R1, R2 and Zis preferably an aryl group having from 6 to 30 carbon atoms. Examplesof the substituent include those described later as the substituent whenZ, R1, R2, Y₁, Y₂, Y₃ and Y₄ can further have a substituent. Inparticular, an electron-withdrawing group is preferred because the dyecan have a noble oxidation potential and can be improved in thefastness. Examples of the electron-withdrawing group include thosehaving a positive Hammett's substituent constant σp value. Among these,preferred are a halogen atom, a heterocyclic group, a cyano group, acarboxyl group, an acylamino group, a sulfonamido group, a sulfamoylgroup, a carbamoyl group, a sulfonyl group, an imido group, an acylgroup, a sulfo group and a quaternary ammonium group, more preferred area cyano group, a carboxyl group, a sulfamoyl group, a carbamoyl group, asulfonyl group, an imido group, an acyl group, a sulfo group and aquaternary ammonium group.

The heterocyclic group represented by R1, R2 and Z is preferably a 5- or6-membered ring and the ring may be further condensed. Also, theheterocyclic group may be an aromatic heterocyclic group or anon-aromatic heterocyclic group. Examples of the heterocyclic grouprepresented by R1, R2 and Z are shown below in the form of aheterocyclic ring by omitting the substitution site. The substitutionsite is not limited and, for example, in the case of pyridine, the2-position, 3-position and 4-position can be substituted. Examplesinclude pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline,isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole,indole, furan, benzofuran, thiophene, benzothiophene, pyrazole,imidazole, benzimidazole, triazole, oxazole, benzoxazole, thiazole,benzothiazole, isothiazole, benzisothiazole, thiadiazole, isoxazole,benzisoxazole, pyrrolidine, piperidine, piperazine, imidazolidine andthiazoline. In particular, an aromatic heterocyclic group is preferred.Preferred examples thereof include, shown in the same manner as above,pyridine, pyrazine, pyrimidine, pyridazine, triazine, pyrazole,imidazole, benzimidazole, triazole, thiazole, benzothiazole,isothiazole, benzisothiazole and thiadiazole. These groups each may havea substituent and examples of the substituent include those describedlater as the substituent when Z, R1, R2, Y₁, Y₂, Y₃ and Y₄ can furtherhave a substituent. Preferred substituents are the same as theabove-described substituents of the aryl group and more preferredsubstituents are the same as the above-described more preferredsubstituents of the aryl group.

Y₁, Y₂, Y₃ and Y₄ each independently represents a hydrogen atom, ahalogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, anaralkyl group, an aryl group, a heterocyclic group, a cyano group, ahydroxyl group, a nitro group, an amino group, an alkylamino group, analkoxy group, an aryloxy group, an acylamino group, an arylamino group,a ureido group, a sulfamoylamino group, an alkylthio group, an arylthiogroup, an alkoxycarbonylamino group, a sulfonamido group, a carbamoylgroup, a sulfamoyl group, a sulfonyl group, an alkoxycarbonyl group, aheterocyclic oxy group, an azo group, an acyloxy group, a carbamoyloxygroup, a silyloxy group, an aryloxycarbonyl group, anaryloxycarbonylamino group, an imido group, a heterocyclic thio group, aphosphoryl group, an acyl group, a carboxyl group or a sulfo group.These groups each may further have a substituent.

Y₁, Y₂, Y₃ and Y₄ each is preferably a hydrogen atom, a halogen atom, analkyl group, an aryl group, a cyano group, an alkoxy group, an amidogroup, a ureido group, a sulfonamido group, a carbamoyl group, asulfamoyl group, an alkoxycarbonyl group, a carboxyl group or a sulfogroup, more preferably a hydrogen atom, a halogen atom, a cyano group, acarboxyl group or a sulfo group, and most preferably a hydrogen atom.

When Z, R1, R2, Y₁, Y₂, Y₃ and Y₄ each is a group which can further havea substituent, the group may further have the following substituent.

Examples of the substituent include a linear or branched alkyl grouphaving from 1 to 12 carbon atoms, a linear or branched aralkyl grouphaving from 7 to 18 carbon atoms, a linear or branched alkenyl grouphaving from 2 to 12 carbon atoms, a linear or branched alkynyl grouphaving from 2 to 12 carbon atoms, a linear or branched cycloalkyl grouphaving from 3 to 12 carbon atoms, a linear or branched cycloalkenylgroup having from 3 to 12 carbon atoms (these groups each is preferablya group having a branched chain because the solubility of dye and thestability of ink are improved, more preferably a group having anasymmetric carbon; specific examples of the groups include methyl,ethyl, propyl, isopropyl, sec-butyl, tert-butyl, 2-ethylhexyl,2-methylsulfonylethyl, 3-phenoxypropyl, trifluoromethyl andcyclopentyl), a halogen atom (e.g., chlorine, bromine), an aryl group(e.g., phenyl, 4-tert-butylphenyl, 2,4-di-tert-amylphenyl), aheterocyclic group (e.g., imidazolyl, pyrazolyl, triazolyl, 2-furyl,2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl), a cyano group, a hydroxylgroup, a nitro group, a carboxy group, an amino group, an alkyloxy group(e.g., methoxy, ethoxy, 2-methoxyethoxy, 2-methanesulfonylethoxy), anaryloxy group (e.g., phenoxy, 2-methylphenoxy, 4-tert-butylphenoxy,3-nitrophenoxy, 3-tert-butyloxycarbamoylphenoxy, 3-methoxycarbamoyl), anacylamino group (e.g., acetamido, benzamido,4-(3-tert-butyl-4-hydroxyphenoxy)butanamido), an alkylamino group (e.g.,methylamino, butylamino, diethylamino, methylbutylamino), an anilinogroup (e.g., phenylamino, 2-chloroanilino), a ureido group (e.g.,phenylureido, methylureido, N,N-dibutylureido), a sulfamoylamino group(e.g., N,N-dipropylsulfamoylamino), an alkylthio group (e.g.,methylthio, octylthio, 2-phenoxyethylthio), an arylthio group (e.g.,phenylthio, 2-butoxy-5-tert-octylphenylthio, 2-carboxyphenylthio), analkyloxycarbonylamino group (e.g., methoxycarbonylamino), a sulfonamidogroup (e.g., methanesulfonamido, benzenesulfonamido,p-toluenesulfonamido), a carbamoyl group (e.g., N-ethylcarbamoyl,N,N-dibutylcarbamoyl), a sulfamoyl group (e.g., N-ethylsulfamoyl,N,N-dipropylsulfamoyl, N-phenylsulfamoyl), a sulfonyl group (e.g.,methanesulfonyl, octanesulfonyl, benzenesulfonyl, toluenesulfonyl), analkyloxycarbonyl group (e.g., methoxycarbonyl, butyloxycarbonyl), aheterocyclic oxy group (e.g., 1-phenyltetrazol-5-oxy,2-tetrahydropyranyloxy), an azo group (e.g., phenylazo,4-methoxyphenylazo, 4-pivaloylaminophenylazo,2-hydroxy-4-propanoylphenylazo), an acyloxy group (e.g., acetoxy), acarbamoyloxy group (e.g., N-methylcarbamoyloxy, N-phenylcarbamoyloxy), asilyloxy group (e.g., trimethylsilyloxy, dibutylmethylsilyloxy), anaryloxycarbonylamino group (e.g., phenoxycarbonylamino), an imido group(e.g., N-succinimido, N-phthalimido), a heterocyclic thio group (e.g.,2-benzothiazolylthio, 2,4-di-phenoxy-1,3,5-triazole-6-thio,2-pyridylthio), a sulfinyl group (e.g., 3-phenoxypropylsulfinyl), aphosphonyl group (e.g., phenoxyphosphonyl, octyloxyphosphonyl,phenylphosphonyl), an aryloxycarbonyl group (e.g., phenoxycarbonyl), anacyl group (e.g., acetyl, 3-phenylpropanoyl, benzoyl), and an ionichydrophilic group (e.g., carboxyl, sulfo, phosphono, quaternaryammonium).

In the case where the phthalocyanine dye represented by formula (I) iswater-soluble, the dye preferably contains an ionic hydrophilic group.Examples of the ionic hydrophilic group include a sulfo group, acarboxyl group, a phosphono group and a quaternary ammonium group. Amongthese ionic hydrophilic groups, preferred are a carboxyl group, aphosphono group and a sulfo group, more preferred are a carboxyl groupand a sulfo group. The carboxyl group, the phosphono group and the sulfogroup each may be in a salt state and examples of the counter ion forforming the salt include ammonium ion, alkali metal ions (e.g., lithiumion, sodium ion, potassium ion) and organic cations (e.g.,tetramethylammonium ion, tetramethylguanidium ion,tetramethylphosphonium). Among these counter ions, alkali metal saltsare preferred and a lithium salt is more preferred because thesolubility of dye and the stability of ink are enhanced.

As for the number of ionic hydrophilic groups, the phthalocyanine dyepreferably contains at least two ionic hydrophilic groups, morepreferably at least two sulfo groups and/or carboxyl groups, within onemolecule.

a₁ to a₄ and b₁ to b₄ represent the number of substituents X₁ to X₄ andY₁ to Y₄, respectively. a₁ to a₄ each independently represents aninteger of 0 to 4 but all are not 0 at the same time. b₁ to b₄ eachindependently represents an integer of 0 to 4. When a₁, a₂, a₃, a₄, b₁,b₂, b₃ or b₄ represents an integer of 2 or more, a plurality of X₁s,X₂s, X₃s, X₄s, Y₁s, Y₂s, Y₃s or Y₄s are present and these may be thesame or different.

a₁ and b₁ satisfy the relationship of a₁+b₁=4. In particular, acombination that a₁ represents 1 or 2 and b₁ represents 3 or 2 ispreferred, and a combination that a₁ represents 1 and b₁ represents 3 ismost preferred.

The same relationship as that between a₁ and b₁ is present in each ofthe pairs a₂ and b₂, a₃ and b₃, and a₄ and b₄, and the preferredcombination is also the same.

M represents a hydrogen atom, a metal element or an oxide, hydroxide orhalide thereof.

M is preferably a hydrogen atom, a metal element such as Li, Na, K, Mg,Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt,Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Si, Ge, Sn, Pb, Sb and Bi, an oxidesuch as VO and GeO, a hydroxide such as Si(OH)₂, Cr(OH)₂ and Sn(OH)₂, ora halide such as AlCl, SiCl₂, VCl, VCl₂, VOCl, FeCl, GaCl and ZrCl, morepreferably Cu, Ni, Zn or Al, and most preferably Cu.

Also, Pc (phthalocyanine ring) may form a dimer (for example,Pc-M-L-M-Pc) or a trimer through L (divalent linking group). At thistime, Ms may be the same or different.

The divalent linking group represented by L is preferably an oxy group—O—, a thio group —S—, a carbonyl group —CO—, a sulfonyl group —SO₂—, animino group —NH—, a methylene group —CH₂— or a group formed by combiningtwo or more of these groups.

As for the preferred combination of substituents in the compoundrepresented by formula (I), a compound where at least one of varioussubstituents is the preferred group is preferred, a compound where alarger number of various substituents are the preferred groups is morepreferred, and a compound where all substituents are the preferredgroups is most preferred.

Among the phthalocyanine dyes represented by formula (I), aphthalocyanine dye having a structure represented by formula (II) ispreferred. The phthalocyanine dye represented by formula (II) of thepresent invention is described in detail below.

In formula (II), X₁₁ to X₁₄ and Y₁₁ to Y₁₈ have the same meanings as X₁to X₄ and Y₁ to Y₄ in formula (I), respectively, and preferred examplesare also the same. M₁ has the same meaning as M in formula (I) andpreferred examples are also the same.

In formula (II), a₁₁ to a₁₄ each independently represents an integer of1 or 2 and preferably satisfy 4≦a₁₁+a₁₂+a₁₃+a₁₄≦6, and a₁₁=a₁₂=a₁₃=a₁₄=1is more preferred.

X₁₁, X₁₂, X₁₃ and X₁₄ may be completely the same substituents, may besubstituents of the same kind but partially different as in the case,for example, where X₁₁, X₁₂, X₁₃ and X₁₄ all are —SO₂-Z and Zs aredifferent from each other, or may include substituents different fromeach other, for example, —SO₂-Z and —SO₂NR1R2.

In the phthalocyanine dye represented by formula (II), the followingcombinations of substituents are particularly preferred.

X₁₁ to X₁₄ each independently represents preferably —SO-Z, —SO₂-Z,—SO₂NR1R2 or —CONR1R2, more preferably —SO₂-Z or —SO₂NR1R2, and mostpreferably —SO₂-Z.

Each Z independently represents preferably a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group ora substituted or unsubstituted heterocyclic group, and most preferably asubstituted alkyl group, a substituted aryl group or a substitutedheterocyclic group. In particular, the case where an asymmetric carbonis present in the substituent (use in the racemic form) is preferredbecause the solubility of dye and the stability of ink are enhanced.Also, the case where a hydroxyl group, an ether group, an ester group, acyano group, an amido group or a sulfonamido group is present in thesubstituent is preferred because the aggregating property and fastnessare improved.

R1 and R2 each independently represents preferably a hydrogen atom, asubstituted or unsubstituted alkyl group, a substituted or unsubstitutedaryl group or a substituted or unsubstituted heterocyclic group, morepreferably a hydrogen atom, a substituted alkyl group, a substitutedaryl group or a substituted heterocyclic group. However, it is notpreferred that R1 and R2 both are a hydrogen atom. In particular, thecase where an asymmetric carbon is present in the substituent (use inthe racemic form) is preferred because the solubility of dye and thestability of ink are enhanced. Also, the case where a hydroxyl group, anether group, an ester group, a cyano group, an amido group or asulfonamido group is present in the substituent is preferred because theaggregating property and fastness are improved.

Y₁₁ to Y₁₈ each independently represents preferably a hydrogen atom, ahalogen atom, an alkyl group, an aryl group, a cyano group, an alkoxygroup, an amido group, a ureido group, a sulfonamido group, a carbamoylgroup, a sulfamoyl group, an alkoxycarbonyl group, a carboxyl group or asulfo group, more preferably a hydrogen atom, a halogen atom, a cyanogroup, a carboxyl group or a sulfo group, and most preferably a hydrogenatom.

a₁₁ to a₁₄ each independently represents preferably 1 or 2 and it ismore preferred that all are 1.

M₁ represents a hydrogen atom, a metal element or an oxide, hydroxide orhalide thereof, preferably Cu, Ni, Zn or Al, and most preferably Cu.

In the case where the phthalocyanine dye represented by formula (II) iswater-soluble, the dye preferably contains an ionic hydrophilic group.Examples of the ionic hydrophilic group include a sulfo group, acarboxyl group, a phosphono group and a quaternary ammonium group. Amongthese ionic hydrophilic groups, preferred are a carboxyl group, aphosphono group and a sulfo group, more preferred are a carboxyl groupand a sulfo group. The carboxyl group, the phosphono group and the sulfogroup each may be in a salt state and examples of the counter ion forforming the salt include ammonium ion, alkali metal ions (e.g., lithiumion, sodium ion, potassium ion) and organic cations (e.g.,tetramethylammonium ion, tetramethylguanidium ion,tetramethylphosphonium). Among these counter ions, alkali metal saltsare preferred and a lithium salt is more preferred because thesolubility of dye and the stability of ink are enhanced.

As for the number of ionic hydrophilic groups, the phthalocyanine dyepreferably contains at least two ionic hydrophilic groups, morepreferably at least two sulfo groups and/or carboxyl groups, within onemolecule.

As for the preferred combination of substituents in the compoundrepresented by formula (II), a compound where at least one of varioussubstituents is the preferred group is preferred, a compound where alarger number of various substituents are the preferred groups is morepreferred, and a compound where all substituents are the preferredgroups is most preferred.

As for the chemical structure of the phthalocyanine dye of the presentinvention, at least one electron-withdrawing group such as sulfinylgroup, sulfonyl group and sulfamoyl group is preferably introduced intorespective four benzene rings of phthalocyanine such that the total ofup values of the substituents in the entire phthalocyanine skeletonbecomes 1.6 or more.

The Hammett's substituent constant up value is briefly described here.The Hammett's rule is an empirical rule advocated by L. P. Hammett in1935 so as to quantitatively discuss the effect of substituent on thereaction or equilibrium of benzene derivatives and its propriety iswidely admitted at present. The substituent constant determined by theHammett's rule includes a σp value and a σm value and these values canbe found in a large number of general publications but these aredescribed in detail, for example, in J. A. Dean (compiler), Lange'sHandbook of Chemistry, 12th ed., McGraw-Hill (1979), and Kagakuno Ryoiki(Chemistry Region), special number, No. 122, pp. 96-103, Nankodo (1979).

Inevitably in view of the synthesis method, the phthalocyaninederivative represented by formula (I) is generally a mixture ofanalogues differing in the site where the substituents Xn (n=1 to 4) andYm (m=1 to 4) are introduced and in the number of the substituentsintroduced. Accordingly, these analogue mixtures are statisticallyaveraged and represented by a formula in many cases. In the presentinvention, it has been found that when these analogue mixtures areclassified into the following three types, a specific mixture isparticularly preferred. The phthalocyanine-base dye analogue mixturesrepresented by formulae (I) and (II) are defined by classifying theseinto the following three types based on the substitution site.

(1) β-Position Substitution Type:

A phthalocyanine dye having specific substituents at the 2- and/or3-position, the 6- and/or 7-position, the 10- and/or 11-position, andthe 14- and/or 15-position.

(2) α-Position Substitution Type:

A phthalocyanine dye having specific substituents at the 1- and/or4-position, the 5- and/or 8-position, the 9- and/or 12-position, and the13- and/or 16-position.

(3) α,β-Position Mixed Substitution Type:

A phthalocyanine dye having specific substitutions at the 1- to16-positions without any regularity.

In the present invention, phthalocyanine dye derivatives differing inthe structure (particularly in the substitution site) are described byusing these β-position substitution type, α-position substitution typeand α,β-position mixed substitution type.

The phthalocyanine derivative for use in the present invention can besynthesized by combining the methods described or cited, for example, inShirai and Kobayashi, Phthalocyanine—Kagaku to Kino—(Phthalocyanine—Chemistry and Function—), pp. 1-62, IPC, and C. C.Leznoff and A. B. P. Lever, Phthalocyanines—Properties and Applications,pp. 1-54, VCH, or methods analogous thereto.

The phthalocyanine compound represented by formula (I) of the presentinvention can be synthesized, for example, through sulfonation, sulfonylchloridation or amidation reaction of an unsubstituted phthalocyaninecompound as described in International Publications 00/17275, 00/08103,00/08101 and 98/41853 and JP-A-10-36471. In this case, sulfonation maytake place at any site of the phthalocyanine nucleus and the number ofsites sulfonated is difficult to control. Accordingly, when a sulfogroup is introduced under such reaction conditions, the positions andnumber of sulfo groups introduced into the product cannot be specifiedand a mixture of those differing in the number of substituents or in thesubstitution site inevitably results. If the compound of the presentinvention is synthesized starting from such a product, the compound ofthe present invention is obtained as an α,β-position mixed substitutiontype mixture containing several kinds of compounds differing in thenumber of substituents or in the substitution site because the number ofsulfamoyl groups substituted on the heterocyclic ring or theirsubstitution sites cannot be specified.

As described above, for example, when many electron-withdrawing groupssuch as sulfamoyl group are introduced into the phthalocyanine nucleus,the oxidation potential becomes more positive and the ozone resistanceis increased. However, according to the above-described synthesismethod, a phthalocyanine dye where the number of electron-withdrawinggroups introduced is small, namely, the oxidation potential is morenegative, is inevitably mingled. Therefore, in order to improve theozone resistance, it is preferred to use a synthesis method where theproduction of a compound having a more negative oxidation potential issuppressed.

The phthalocyanine compound represented by formula (II) of the presentinvention can be synthesized, for example, by reacting a phthalonitrilederivative (Compound P) shown below and/or a diiminoisoindolinederivative (Compound Q) shown below with a metal derivative representedby formula (III) or can be derived from a tetrasulfophthalocyaninecompound obtained by reacting a 4-sulfophthalonitrile derivative(Compound R) shown below with a metal derivative represented by formula(III).

In the formulae above, X_(p) corresponds to X₁₁, X₁₂, X₁₃ or X₁₄ informula (II) and Y_(q) and Y_(q′) each corresponds to Y₁₁, Y₁₂, Y₁₃,Y₁₄, Y₁₅, Y₁₆, Y₁₇ or Y₁₈ in formula (II). In Compound R, M′ representscation.

Examples of the cation represented by M′ include alkali metal ions suchas Li, Na and K, and organic cations such as triethylammonium ion andpyridinium ion.

Formula (III):M-(Y)_(d)wherein M has the same meaning as M in formulae (I) and (II), Yrepresents a monovalent or divalent ligand such as halogen atom, acetateanion, acetylacetonate and oxygen, and d represents an integer of 1 to4.

That is, according to this synthesis method, a specific number ofdesired substituents can be introduced. Particularly, in the case ofintroducing a large number of electron-withdrawing groups so as torender the oxidation potential more positive as in the presentinvention, this synthesis method is very excellent as compared with theabove-described method for synthesizing the phthalocyanine compound offormula (I).

The thus-obtained phthalocyanine compound represented by formulae (II)is usually a mixture of compounds represented by the following formulae(a)-1 to (a)-4 which are isomers with respect to the substitution siteof each X_(p), namely, a β-position substitution type.

In the synthesis method above, when all X_(p)s are the same, aβ-position substitution type phthalocyanine dye where X₁₁, X₁₂, X₁₃ andX₁₄ are completely the same substituents can be obtained. On the otherhand, when X_(p)s are different, a dye having substituents of the samekind but partially different from each other or a dye havingsubstituents different from each other can be synthesized. Among thedyes of formula (II), these dyes having electron-withdrawingsubstituents different from each other are preferred because thesolubility and aggregating property of dye and the aging stability ofink can be controlled.

In the present invention, it has been found very important for theimprovement of fastness that in any substitution type, the oxidationpotential is more positive than 1.0 V (vs SCE). The great effect thereofcannot be expected at all from the above-described known techniques.Furthermore, although the reason is not particularly known, there is atendency that the β-position substitution type is apparently moreexcellent in the color hue, light fastness, ozone gas resistance and thelike than the α,β-position mixed substitution type.

Specific examples (Compounds I-1 to I-12 and 101 to 190) of thephthalocyanine dyes represented by formulae (I) and (II) are set forthbelow, however, the phthalocyanine dye for use in the present inventionis not limited to the following examples.

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular order.M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 101 Cu —SO₂—NH—CH₂—CH₂—SO₃Li—H —H, —H —H, —H —H, —H —H, —H 102 Cu

—H —Cl, —H —Cl, —H —Cl, —H —Cl, —H 103 Cu

—H —H, —H —H, —H —H, —H —H, —H 104 Cu

—H —H, —H —H, —H —H, —H —H, —H 105 Ni

—H —Cl, —H —Cl, —H —Cl, —H —Cl, —H 106 Cu—SO₂—NH—CH₂—CH₂—SO₂—NH—CH₂—COONa —CN —H, —H —H, —H —H, —H —H, —H 107 Cu

—H —H, —H —H, —H —H, —H —H, —H 108 Cu —SO₂—CH₂—CH₂—CH₂—SO₃Li —H —H, —H—H, —H —H, —H —H, —H 109 Cu —SO₂—CH₂—CH₂—CH₂—SO₃K —H —H, —H —H, —H —H,—H —H, —H 110 Cu —SO₂—(CH₂)₅—CO₂K —H —H, —H —H, —H —H, —H —H, —H

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular orderM X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 111 Cu

—H —H, —H —H, —H —H, —H —H, —H 112 Cu

—SO₃Li —H, —H —H, —H —H, —H —H, —H 113 Cu

—H —H, —H —H, —H —H, —H —H, —H 114 Cu

—SO₃Li —H, —H —H, —H —H, —H —H, —H 115 Cu

—H —H, —H —H, —H —H, —H —H, —H 116 Cu

—H —H, —H —H, —H —H, —H —H, —H 117 Cu

—H —H, —H —H, —H —H, —H —H, —H

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular order.M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 118 Cu

—H —H, —H —H, —H —H, —H —H, —H 119 Cu

—H —H, —H —H, —H —H, —H —H, —H 120 Cu

—H —H, —H —H, —H —H, —H —H, —H 121 Cu

—H —H, —H —H, —H —H, —H —H, —H 122 Cu

—H —H, —H —H, —H —H, —H —H, —H 123 Cu —SO₂NH—C₈H₁₇(t) —H —H, —H —H, —H—H, —H —H, —H 124 Cu

—H —H, —H —H, —H —H, —H —H, —H

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular order.M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 125 Cu

—H —H, —H —H, —H —H, —H —H, —H 126 Cu

—H —H, —H —H, —H —H, —H —H, —H 127 Cu

—H —H, —H —H, —H —H, —H —H, —H 128 Zn

—CN —H, —H —H, —H —H, —H —H, —H 129 Cu

—H —Cl, —H —Cl, —H —Cl, —H —Cl, —H 130 Cu

—H —H, —H —H, —H —H, —H —H, —H 131 Cu

—H —H, —H —H, —H —H, —H —H, —H

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular order.M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 132 Cu

—H —H, —H —H, —H —H, —H —H, —H 133 Cu

—H —H, —H —H, —H —H, —H —H, —H 134 Cu

—H —H, —H —H, —H —H, —H —H, —H 135 Cu

—H —H, —H —H, —H —H, —H —H, —H 136 Cu

—H —H, —H —H, —H —H, —H —H, —H

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular order.M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 137 Cu

—H —H, —H —H, —H —H, —H —H, —H 138 Cu

—H —H, —H —H, —H —H, —H —H, —H 139 Cu

—Cl —H, —H —H, —H —H, —H —H, —H 140 Cu

—H —H, —H —H, —H —H, —H —H, —H

In Tables, specific examples of each pair of (X1, X2), (Y11, Y12), (Y13,Y14), (Y15, Y16) and (Y17, Y18) are independently in an irregular order.Y11, Y13, M X1 X2 Y12, Y14 Y15, Y16 Y17, Y18 141 Cu

—H —H, —H —H, —H —H, —H —H, —H 142 Cu

—H —H, —H —H, —H —H, —H —H, —H 143 Cu

—H —H, —H —H, —H —H, —H —H, —H 144 Cu

—H —H, —H —H, —H —H, —H —H, —H 145 Cu —SO₂CH₂CH₂OCH₂CH₂OCH₂CH₂SO₃Li —H—H, —H —H, —H —H, —H —H, —H

M-Pc(Xp₁)_(m)(Xp₂)_(n) In Tables, each introduction site of substituents(X_(p1)) and (X_(p2)) is in an irregular order within the β-positionsubstitution type. M Xp₁ m 146 Cu

3 147 Cu —SO₂—NH—CH₂—CH₂SO₃Li 3 148 Cu

3 149 Cu

2 150 Cu —SO₂—NH—CH₂—CH₂—SO₂—NH—CH₂CH₂—COONa 3 151 Cu

3 152 Cu

2.5 153 Cu

2 154 Cu —SO₂—CH₂—CH₂—CH₂—SO₃Li 3 155 Cu —SO₂—CH₂—CH₂—CH₂—COOK 2 156 Cu—SO₂—CH₂—CH₂—CH₂—SO₃Li 3 157 Cu —SO₂—CH₂—CH₂—O—CH₂—CH₂—SO₃Li 2 Xp₂ n 146

1 147

1 148 —SO₂NH—CH₂—CH₂—CH₂—SO₂—NH—CH₂—CH₂—O—CH₂—CH₂—OH 1 149

2 150

1 151 —SO₂NH—CH₂—CH₂—O—CH₂—CH₂—OH 1 152 —SO₂—CH₂—CH₂—O—CH₂—CH₂—OH 1.5153

2 154

1 155

2 156

1 157

2

M-Pc(Xp₁)_(m)(Xp₂)_(n) In Tables, each introduction site of substituents(X_(p1)) and (X_(p2)) is in an irregular order within the β-positionsubstitution type. M Xp₁ m 158 Cu

3 159 Cu —SO₂NHCH₂CH₂—SO₃Li 3 160 Cu—SO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—SO₃Na 3 161 Cu —SO₂CH₂CH₂CH₂SO₃Li 3 162Cu —SO₂CH₂CH₂CH₂SO₃Li 2 163 Cu —SO₂CH₂CH₂CH₂SO₃K 3 164 Cu—SO₂CH₂CH₂CH₂SO₃Li 2 165 Cu —CO—NH—CH₂—CH₂—SO₃K 3 166 Cu—CO—NH—CH₂—CH₂—SO₂—NH—CH₂—CH₂—COONa 3 167 Cu

2.5 168 Cu

2 169 Cu —CO₂—CH₂—CH₂—CH₂—SO₃Li 3 170 Cu —CO₂—CH₂—CH₂—CH₂COOK 2 Xp₁ n158

1 159

1 160

1 161

1 162 —SO₂CH₂CH₂OCH₂CH₂OCH₂CH₂OH 2 163

1 164 —SO₂CH₂CH₂CH₂SO₂N(CH₂CH₂OH)₂ 2 165 —CO—NH—CH₂—CH₂—O—CH₂—CH₂—OH 1166

1 167

1.5 168

2 169

1 170

2

M-Pc(Xp₁)_(m)(Xp₂)_(n) In Tables, each introduction site of substituents(X_(p1)) and (X_(p2)) is in an irregular order within the β-positionsubstitution type. M Xp₁ m 171 Cu —CO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—SO₃Na3 172 Cu —SO₂CH₂CH₂OCH₂CH₂O—CH₂CH₂SO₃K 2 173 Cu

2 174 Cu

3 175 Cu —SO₂(CH₂)₃SO₂NH(CH₂)₃N(CH₂CH₂OH)₂ 2 176 Cu

3 177 Cu —SO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₃ 2 178 Cu—SO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—OH 3 179 Cu

2 180 Cu

3 181 Cu

3 182 Cu

2.5 Xp₂ n 171

1 172

2 173

2 174

1 175

2 176

1 177

1 178

1 179

2 180 —SO₂NH—CH₂—CH₂—SO₂NH—CH₂—CH₂—O—CH₂—CH₂—OH 1 181

1 182

1.5

M-Pc(Xp₁)_(m)(Xp₂)_(n) In Tables, each introduction site of substituents(X_(p1)) and (X_(p2)) is in an irregular order within the β-positionsubstitution type. M Xp₁ m 183 Cu

2 184 Cu

3 185 Cu

3 186 Cu

3 187 Cu

3 188 Cu

3 189 Cu

3 190 Cu

3 Xp₂ n 183 —SO₂—CH₂—CH₂—CH₂—SO₂—NH—(CH₂)₃—CH₂—O—CH₂CH₂—OH 2 184—SO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₃ 1 185—SO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—O—CH₃ 1 186—SO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₂—CH₂—OH 1 187

1 188 —CO₂—CH₂—CH₂—O—CH₂—CH₂—O—CH₃ 1 189

1 190 —CO—NH—CH₂—CH₂—O—CH₂—CH₂—O—CH₃ 1

The structure of the phthalocyanine compound represented byM-Pc(X_(p1))_(m)(X_(p2))_(n) in Compound Nos. 146 to 190 is shown below:

(wherein each X_(p1) is independently X_(p1) or X_(p2)).

The phthalocyanine dye represented by formula (I) can be synthesizedaccording to the patent publications described above. Furthermore, thephthalocyanine dye represented by formula (II) can be synthesized by themethods described in JP-A-2001-226275, JP-A-2001-96610, JP-A-2001-47013and JP-A-2001-193638 in addition to the above-described synthesismethod. The starting material, dye intermediate and synthesis route arenot limited to those described in these patent publications.

The inkjet recording ink of the present invention contains thephthalocyanine dye in an amount of preferably from 0.2 to 20 mass %,more preferably from 0.5 to 15 mass %.

The inkjet recording ink of the present invention can be prepared bydissolving and/or dispersing the phthalocyanine dye in an aqueousmedium. The term “aqueous medium” as used in the present invention meanswater or a mixture of water and a slight amount of water-miscibleorganic solvent, where additives such as wetting agent (preferably asurfactant as a dissolution or dispersion aid), stabilizer andantiseptic are added, if desired.

Examples of the water-miscible organic solvent which can be used in thepresent invention include alcohols (e.g., methanol, ethanol, propanol,isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, pentanol,hexanol, cyclohexanol, benzyl alcohol), polyhydric alcohols (e.g.,ethylene glycol, diethylene glycol, triethylene glycol, polyethyleneglycol, propylene glycol, dipropylene glycol, polypropylene glycol,butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol,thiodiglycol), glycol derivatives (e.g., ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,diethylene glycol monomethyl ether, diethylene glycol monobutyl ether,propylene glycol monomethyl ether, propylene glycol monobutyl ether,dipropylene glycol monomethyl ether, triethylene glycol monomethylether, ethylene glycol diacetate, ethylene glycol monomethyl etheracetate, triethylene glycol monomethyl ether, triethylene glycolmonoethyl ether, ethylene glycol monophenyl ether), amines (e.g.,ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine,N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine,diethylenetriamine, triethylenetetramine, polyethyleneimine,tetramethylpropylenediamine) and other polar solvents (e.g., formamide,N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide,sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone,2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone).These water-miscible organic solvents can be used in combination of twoor more thereof.

The content of the water-miscible organic solvent for use in the presentinvention is usually from 1 to 80 mass %, preferably from 5 to 60 mass%, more preferably from 10 to 50 mass %, in the ink.

Out of those water-miscible organic solvents, if only an organic solventhaving a high boiling point is used, this causes a problem that theformed image is readily blurred under high-humidity condition.

This problem can be solved by using, as the water-miscible organicsolvent, at least one organic solvent having a boiling point of 150° C.or more and at least one organic solvent having a boiling point of lessthan 150° C.

Out of those solvents, examples of the low-boiling point solvent havinga boiling point of less than 150° C. include methanol, ethanol,n-propanol, i-propanol, n-butanol, 2-butanol, tert-butanol,2-methoxyethanol, 1-methoxy-2-propanol, 2-methoxy-1-propanol, acetoneand acetonitrile. Among these, alcohol-base solvents are preferred.

The organic solvent having a boiling point of 150° C. or more can beselected from those described above, but this organic solvent is alsopreferably an alcohol-based solvent.

Also, two or more low-boiling solvents and two or more high-boilingpoint solvents may be selected and used. The percentage of thelow-boiling point solvent in the entire organic solvent is preferablyfrom 1 to 80 mass %, more preferably from 5 to 50 mass %.

It is also preferred to contain, as the water-miscible organic solvent,a mixture of two or more members where at least one member contains apolyhydric alcohol and/or a derivative thereof, at a concentration of 10to 60 (mass/volume) %.

Examples of the polyhydric alcohol include those described above andexamples of the polyhydric alcohol derivative include glycolderivatives. Examples of the glycol derivative include those describedabove.

In this case, the water-miscible organic solvent may be constituted byonly two or more polyhydric alcohols, by only two or more polyhydricalcohol derivatives or by one or more polyhydric alcohol and one or morepolyhydric alcohol derivative.

The proportion of the polyhydric alcohol and/or a derivative thereofcontained in the water-miscible organic solvent is preferably from 15 to55 mass %, more preferably from 20 to 50 mass %.

Out of those water-miscible organic solvents, if a solvent in which thedye has a high solubility is used in a large amount, this also causes aproblem that the formed image is readily blurred under high-humiditycondition.

This problem can be solved when an organic solvent in which the dye hasa solubility of 10 (g/100 g-solvent) or more at 25° C. is contained asthe water-miscible organic solvent to a content of 10 mass % or less inthe ink.

The “solubility” as used herein indicates the mass of a solutedissolvable in 100 g of a solvent at a constant temperature and the unitthereof is “g/100 g-solvent”.

As for the organic solvent in which the dye has a solubility of 10(g/100 g-solvent) or more at 25° C., among those water-miscible organicsolvents, alcohol-base solvents are particularly preferred.

The content of the solvent in which the dye has a solubility of 10 g/100g-solvent or more at 25° C. is 10 mass % or less, preferably 5 mass % orless, in the ink.

Out of those water-miscible organic solvents, if an organic solventhaving a heteroatom other than oxygen is used, this also causes aproblem that the formed image is readily blurred under high-humiditycondition.

Therefore, an organic solvent not containing a heteroatom other than anoxygen atom is preferably used as the water-miscible organic solvent.

Examples of the organic solvent having a heteroatom other than an oxygenatom include, out of those water-miscible organic solvents,thiodiglycol, amines (e.g., ethanolamine, diethanolamine,triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine,morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine,triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine)and other polar solvents (e.g., formamide, N,N-dimethylformamide,N,N-dimethylacetamide, dimethylsulfoxide, sulfolane, 2-pyrrolidone,N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone,1,3-dimethyl-2-imidazolidinone, acetonitrile).

Accordingly, the organic solvent not containing a heteroatom other thanan oxygen atom includes, out of those water-miscible organic solvents,the organic solvents excluding the above-described organic solventshaving a heteroatom other than an oxygen atom.

The organic solvent as used herein indicates an organic solvent which isused as the main solvent for the preparation of ink, and does notinclude a pH adjusting agent used for adjusting the pH of ink, such asorganic acids and amines, and a surfactant used for controlling thesurface tension. Preferred examples of the organic solvent used hereinclude alcohols, polyhydric alcohols (e.g., diol, triol) and glycolderivatives.

Out of those water-miscible organic solvents, if an organic solventhaving a high vapor pressure is used, this causes a problem that theejection stability is impaired due to drying of ink at the inkjet head.

Therefore, a water-miscible organic solvent having a vapor pressure of2,000 Pa or less at 20° C. and exerting a drying inhibiting function ora penetration accelerating function is preferably contained.

The drying inhibiting function is a function of preventing clogging dueto drying of ink at the ejection port and specific examples of thewater-miscible organic solvent having such a function include polyhydricalcohols as represented by ethylene glycol, propylene glycol, diethyleneglycol, polyethylene glycol, thiodiglycol, dithiodiglycol,2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycolderivative, glycerin and trimethylolpropane; lower alkyl ethers ofpolyhydric alcohol, such as ethylene glycol monomethyl(or ethyl) ether,diethylene glycol monomethyl(or ethyl) ether and triethylene glycolmonoethyl(or butyl) ether; heterocyclic rings such as 2-pyrrolidone,N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone andN-ethylmorpholine; sulfur-containing compounds such as sulfolane,dimethylsulfoxide and 3-sulfolene; polyfunctional compounds such asdiacetone alcohol and diethanolamine; and urea derivatives. Among these,preferred are polyhydric alcohols such as glycerin and diethyleneglycol.

The penetration accelerating function is a function of more successfullypenetrating the ink into paper and examples of the water-miscibleorganic solvent having such a function include lower monoalkyl ethers ofpolyhydric alcohol (for example, monomethyl ether, monoethyl ether,mono-n-butyl ether, mono-iso-butyl ether and mono-n-hexyl ether ofethylene glycol, diethylene glycol, triethylene glycol, propylene glycolor dipropylene glycol) and lower dialkyl ethers of polyhydric alcohol(for example, dimethyl ether and diethyl ether of ethylene glycol,diethylene glycol, triethylene glycol or propylene glycol).

The water-miscible organic solvent used here may have two or more ofthese functions and other functions such as viscosity adjustingfunction, in combination.

Incidentally, a water-miscible organic solvent having a vapor pressureexceeding 2,000 Pa at 20° C. can be used in an amount of 20 mass % orless in the ink. Examples of the water-miscible organic solvent otherthan the water-miscible organic solvent having a vapor pressureexceeding 2,000 Pa at 20° C., which can be used in combination, includeethanol.

In the case where the phthalocyanine dye is an oil-soluble dye, theinkjet recording ink can be prepared by dissolving the oil-soluble dyein a high boiling point organic solvent and emulsion-dispersing it in anaqueous medium.

The high boiling point organic solvent for use in the present inventionpreferably has a boiling point of 150° C. or more, more preferably 170°C. or more.

Examples of the high boiling point organic solvent include phthalic acidesters (e.g., dibutyl phthalate, dioctyl phthalate, dicyclohexylphthalate, di-2-ethylhexyl phthalate, decyl phthalate,bis(2,4-di-tert-amylphenyl) isophthalate, bis(1,1-diethylpropyl)phthalate), esters of phosphoric acid or phosphone (e.g., diphenylphosphate, triphenyl phosphate, tricresyl phosphate,2-ethylhexyldiphenyl phosphate, dioctylbutyl phosphate, tricyclohexylphosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate,di-2-ethylhexylphenyl phosphate), benzoic acid esters (e.g.,2-ethylhexyl benzoate, 2,4-dichlorobenzoate, dodecyl benzoate,2-ethylhexyl-p-hydroxybenzoate), amides (e.g., N,N-diethyldodecanamide,N,N-diethyllaurylamide), alcohols or phenols (e.g., isostearyl alcohol,2,4-di-tert-amylphenol), aliphatic esters (e.g., dibutoxyethylsuccinate, di-2-ethylhexyl succinate, 2-hexyldecyl tetradecanoate,tributyl citrate, diethyl azelate, isostearyl lactate, trioctylcitrate), aniline derivatives (e.g.,N,N-dibutyl-2-butoxy-5-tertoctylaniline), chlorinated paraffins (e.g.,paraffins having a chlorine content of 10 to 80%), trimesic acid esters(e.g., tributyl trimesate), dodecylbenzene, diisopropylnaphthalene,phenols (e.g., 2,4-di-tert-amylphenol, 4-dodecyloxyphenol,4-dodecyloxycarbonylphenol, 4-(4-dodecyloxyphenylsulfonyl)phenol),carboxylic acids (e.g., 2-(2,4-di-tert-amylphenoxy)butyric acid,2-ethoxyoctanedecanoic acid) and alkylphosphoric acids (e.g.,di-(2-ethylhexyl)phosphoric acid and diphenylphosphoric acid).

The high boiling point organic solvent can be used in an amount of, interms of the mass ratio to the oil-soluble dye, from 0.01 to 3 times,preferably from 0.01 to 1.0 times.

These high boiling point organic solvents may be used individually or asa mixture of several kinds [for example, tricresyl phosphate and dibutylphthalate, trioctyl phosphate and di(2-ethylhexyl) sebacate, or dibutylphthalate and poly(N-tert-butylacrylamide)].

Examples of the high boiling point organic solvent for use in thepresent invention, other than the above-described compounds, and thesynthesis method of these high boiling point organic solvents aredescribed, for example, in U.S. Pat. Nos. 2,322,027, 2,533,514,2,772,163, 2,835,579, 3,594,171, 3,676,137, 3,689,271, 3,700,454,3,748,141, 3,764,336, 3,765,897, 3,912,515, 3,936,303, 4,004,928,4,080,209, 4,127,413, 4,193,802, 4,207,393, 4,220,711, 4,239,851,4,278,757, 4,353,979, 4,363,873, 4,430,421, 4,430,422, 4,464,464,4,483,918, 4,540,657, 4,684,606, 4,728,599, 4,745,049, 4,935,321 and5,013,639, EP-A-276319, EP-A-286253, EP-A-289820, EP-A-309158,EP-A-309159, EP-A-309160, EP-A-509311, EP-A-510576, East German Patents147,009, 157, 147, 159,573 and 225,240A, British Patent 2091124A,JP-A-48-47335, JP-A-50-26530, JP-A-51-25133, JP-A-51-26036,JP-A-51-27921, JP-A-51-27922, JP-A-51-149028, JP-A-52-46816,JP-A-53-1520, JP-A-53-1521, JP-A-53-15127, JP-A-53-146622,JP-A-54-91325, JP-A-54-106228, JP-A-54-118246, JP-A-55-59464,JP-A-56-64333, JP-A-56-81836, JP-A-59-204041, JP-A-61-84641,JP-A-62-118345, JP-A-62-247364, JP-A-63-167357, JP-A-63-214744,JP-A-63-301941, JP-A-64-9452, JP-A-64-9454, JP-A-64-68745,JP-A-1-101543, JP-A-1-102454, JP-A-2-792, JP-A-2-4239, JP-A-2-43541,JP-A-4-29237, JP-A-4-30165, JP-A-4-232946 and JP-A-4-346338.

In the present invention, the oil-soluble dye or high boiling pointorganic solvent is used by emulsion-dispersing it in an aqueous medium.Depending on the case, a low boiling point organic solvent may be usedin combination at the emulsion-dispersion in view of emulsifiability.The low boiling point organic solvent which can be used in combinationis an organic solvent having a boiling point of about 30 to 150° C. atatmospheric pressure. Preferred examples thereof include, but are notlimited to, esters (e.g., ethyl acetate, butyl acetate, ethylpropionate, β-ethoxyethyl acetate, methylcellosolve acetate), alcohols(e.g., isopropyl alcohol, n-butyl alcohol, secondary butyl alcohol),ketones (e.g., methyl isobutyl ketone, methyl ethyl ketone,cyclohexanone), amides (e.g., dimethylformamide, N-methylpyrrolidone)and ethers (e.g., tetrahydrofuran, dioxane).

In the emulsion-dispersion, an oil phase obtained by dissolving the dyein a high boiling organic solvent or depending on the case, in a mixedsolvent of a high boiling organic solvent and a low boiling organicsolvent is dispersed in an aqueous phase mainly comprising water to formfine oil droplets of the oil phase. At this time, in either one or bothof the aqueous phase and the oil phase, additives described later, suchas surfactant, wetting agent, dye stabilizer, emulsification stabilizer,antiseptic and fungicide, can be added, if desired.

In the general emulsification method, an oil phase is added to anaqueous phase, however, a so-called phase inversion emulsificationmethod of adding dropwise an aqueous phase in an oil phase can also bepreferably used.

In performing the emulsion-dispersion of the present invention, varioussurfactants can be used. Preferred examples thereof include anionicsurfactants such as fatty acid salt, alkylsulfuric ester salt,alkylbenzenesulfonate, alkylnaphthalenesulfonate, dialkylsulfosuccinate,alkylphosphoric ester salt, naphthalenesulfonic acid formalin condensateand polyoxyethylene alkylsulfuric ester salt, and nonionic surfactantssuch as polyoxyethylene alkyl ether, polyoxyethylene alkylallyl ether,polyoxyethylene fatty acid ester, sorbitan fatty acid ester,polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine,glycerin fatty acid ester and oxyethylene oxypropylene block copolymer.Also, SURFYNOLS (produced by Air Products & Chemicals), which are anacetylene-base polyoxyethylene oxide surfactant, are preferably used.Furthermore, amine oxide-type amphoteric surfactants such asN,N-dimethyl-N-alkylamine oxide are preferred. In addition, surfactantsdescribed in JP-A-59-157636 (pages (37) to (38)) and ResearchDisclosure, No. 308119 (1989) can also be used.

The surfactant used for emulsification is differing in the purpose fromthe surfactant added for adjusting the liquid properties of the inkjetrecording ink, which is described later, but the same surfactant can beused and if the case is so, the function of adjusting the properties ofink can be exerted as a result.

For the purpose of stabilizing the dispersion immediately afteremulsification, a water-soluble polymer may be added in combination withthe surfactant. Preferred examples of the water-soluble polymer includepolyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyacrylicacid, polyacrylamide and copolymers thereof. Other than these, naturalwater-soluble polymers such as polysaccharides, casein and gelatin arealso preferably used.

Furthermore, for the stabilization of dye dispersion, a polymer whichdoes not substantially dissolve in an aqueous medium, such as polyvinyl,polyurethane, polyester, polyamide, polyurea and polycarbonate obtainedby the polymerization of acrylic acid esters, methacrylic acid esters,vinyl esters, acrylamides, methacrylamides, olefins, styrenes, vinylethers or acrylonitriles, can also be used in combination. This polymerpreferably contains —SO²⁻ or —COO⁻. In the case of using this polymerwhich does not substantially dissolve in an aqueous medium, the polymeris preferably used in an amount of 20 mass % or less, more preferably 10mass % or less, based on the high boiling point organic solvent.

In preparing an aqueous ink by dispersing the oil-soluble dye or highboiling point organic solvent according to emulsion-dispersion, a matterof importance is the control of particle size. In order to elevate thecolor purity or density of an image formed by the inkjet recording, itis essential to reduce the average particle size. The average particlesize is, in terms of the volume average particle size, preferably 1 μmor less, more preferably from 5 to 100 nm.

The volume average particle size and particle size distribution of thedispersed particles can be easily measured by a known method such asstatic light scattering method, dynamic light scattering method,centrifugal precipitation method and the method described in JikkenKagaku Koza (Lecture of Experimental Chemistry), 4th ed., pp. 417-418.

For example, the ink is diluted with distilled water to have a particleconcentration of 0.1 to 1 mass %, then, the particle size can be easilymeasured by a commercially available volume average particle sizemeasuring apparatus (for example, Microtrac UPA (manufactured by NikkisoK.K.)). The dynamic light scattering method utilizing the laser Dopplereffect is particularly preferred because even a small particle size canbe measured.

The volume average particle size is an average particle size weightedwith the particle volume and is obtained by multiplying the diameter ofindividual particles in the gathering of particles with the volume ofthe particle and dividing the sum total of the obtained values by thetotal volume of the particles. The volume average particle size isdescribed in Soichi Muroi, Kobunshi Latex no Kagaku (Chemistry ofPolymer Latex), page 119, Kobunshi Kanko Kai.

Also, it is revealed that the presence of coarse particles greatlyaffects the printing performance. More specifically, the coarse particleclogs the nozzle of head or even if the nozzle is not clogged, forms asoil to bring about ejection failure or ejection slippage of ink andthis seriously affects the printing performance. In order to preventthese troubles, it is important to reduce the number of particles havinga particle size of 5 μm or more to 10 or less and the number ofparticles having a particle size of 1 μm or more to 1,000 or less, in 1μl of ink prepared.

For removing these coarse particles, a known method such as centrifugalseparation or microfiltration can be used. This separation step may beperformed immediately after the emulsion-dispersion or may be performedimmediately before filling the ink in an ink cartridge after variousadditives such as wetting agent and surfactant are added to theemulsified dispersion.

A mechanically emulsifying apparatus is effective for reducing theaverage particle size and eliminating coarse particles.

As for the emulsifying apparatus, known apparatuses such as simplestirrer, impeller stirring system, in-line stirring system, mill system(e.g., colloid mill) and ultrasonic system can be used, but ahigh-pressure homogenizer is particularly preferred.

The mechanism of the high-pressure homogenizer is described in detail inU.S. Pat. No. 4,533,254 and JP-A-6-47264. Examples of the commerciallyavailable apparatus include Gaulin Homogenizer (manufactured by A.P.VGaulin Inc.), Microfluidizer (manufactured by Microfluidex Inc.) andAltimizer (produced by Sugino Machine).

The high-pressure homogenizer with a mechanism of pulverizing particlesin an ultrahigh pressure jet stream recently described in U.S. Pat. No.5,720,551 is particularly effective for the emulsion-dispersion of thepresent invention. Examples of the emulsifying apparatus using thisultrahigh pressure jet stream include DeBEE2000 (manufactured by BEEInternational Ltd.).

In performing the emulsification by a high-pressure emulsion-dispersingapparatus, the pressure is 50 MPa or more, preferably 60 MPa or more,more preferably 180 MPa or more.

A method of using two or more emulsifying apparatuses, for example, byperforming the emulsification in a stirring emulsifier and then passingthe emulsified product through a high-pressure homogenizer isparticularly preferred. Also, a method of once performing theemulsion-dispersion by such an emulsifying apparatus and after addingadditives such as wetting agent and surfactant, again passing thedispersion through a high-pressure homogenizer during filling of the inkinto a cartridge is preferred.

In the case of containing a low boiling point organic solvent inaddition to the high boiling point organic solvent, the low boilingpoint solvent is preferably removed in view of stability of theemulsified product, safety and hygiene. For removing the low boilingpoint solvent, various known methods can be used according to the kindof the solvent. Examples of the method include evaporation, vacuumevaporation and ultrafiltration. This removal of the low boiling pointorganic solvent is preferably performed as soon as possible immediatelyafter the emulsification.

The inkjet recording ink of the present invention may contain asurfactant to control the liquid properties of the ink, wherebyexcellent effects can be provided, such as enhancement of ejectionstability of ink, improvement of water resistance of image, andprevention of bleeding of printed ink.

Examples of the surfactant include anionic surfactants such as sodiumdodecylsulfate, sodium dodecyloxysulfonate and sodiumalkylbenzenesulfonate, cationic surfactants such as cetylpyridiniumchloride, trimethylcetylammonium chloride and tetrabutylammoniumchloride, and nonionic surfactants such as polyoxyethylene nonylphenylether, polyoxyethylene naphthyl ether and polyoxyethylene octylphenylether. Among these, nonionic surfactants are preferred.

The surfactant content is preferably from 0.001 to 15 mass %, morepreferably from 0.005 to 10 mass %, still more preferably from 0.01 to 5mass %, in the ink.

In the inkjet recording ink of the present invention, additives such asdrying inhibitor for preventing clogging due to drying of ink at theejection port, penetration accelerator for more successfully penetratingthe ink into paper, ultraviolet absorbent, antioxidant, viscosityadjusting agent, surface tension adjusting agent, dispersant, dispersionstabilizer, fungicide, rust inhibitor, pH adjusting agent, defoamingagent and chelating agent, may be appropriately selected and used in anappropriate amount.

The drying inhibitor for use in the present invention is preferably awater-soluble organic solvent having a vapor pressure lower than water.Specific examples thereof include polyhydric alcohols as represented byethylene glycol, propylene glycol, diethylene glycol, polyethyleneglycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol,1,2,6-hexanetriol, acetylene glycol derivative, glycerin andtrimethylolpropane; lower alkyl ethers of polyhydric alcohol, such asethylene glycol monomethyl(or ethyl) ether, diethylene glycolmonomethyl(or ethyl) ether and triethylene glycol monoethyl(or butyl)ether; heterocyclic rings such as 2-pyrrolidone, N-methyl-2-pyrrolidone,1,3-dimethyl-2-imidazolidinone and N-ethylmorpholine; sulfur-containingcompounds such as sulfolane, dimethylsulfoxide and 3-sulfolene;polyfunctional compounds such as diacetone alcohol and diethanolamine;and urea derivatives. Among these, polyhydric alcohols such as glycerinand diethylene glycol are preferred. These drying inhibitors may be usedindividually or in combination of two or more thereof. The dryinginhibitor is preferably contained in an amount of 10 to 50 mass % in theink.

Examples of the penetration accelerator which can be used in the presentinvention include alcohols such as ethanol, isopropanol, butanol,di(tri)ethylene glycol monobutyl ether and 1,2-hexanediol, sodiumlaurylsulfate, sodium oleate and nonionic surfactants. A sufficientlyhigh effect can be obtained by adding from 10 to 30 mass % of thepenetration accelerator in the ink. The penetration accelerator ispreferably used in an amount of causing no blurring of printed letter orno print through.

Examples of the ultraviolet absorbent which can be used in the presentinvention for improving the preservability of image includebenzotriazole-base compounds described in JP-A-58-185677,JP-A-61-190537, JP-A-2-782, JP-A-5-197075 and JP-A-9-34057,benzophenone-base compounds described in JP-A-46-2784, JP-A-5-194483 andU.S. Pat. No. 3,214,463, cinnamic acid-base compounds described inJP-B-48-30492 (the term “JP-B” as used herein means an “examinedJapanese patent publication”), JP-B-56-21141 and JP-A-10-88106,triazine-base compounds described in JP-A-4-298503, JP-A-8-53427,JP-A-8-239368, JP-A-10-182621 and JP-T-8-501291, compounds described inResearch Disclosure No. 24239, and compounds of absorbing ultravioletlight and emitting fluorescent light, so-called fluorescent brighteningagents, as represented by stilbene-base compounds and benzoxazole-basecompounds.

As for the antioxidant which is used in the present invention forimproving the preservability of image, various organic or metalcomplex-base discoloration inhibitors can be used. Examples of theorganic discoloration inhibitor include hydroquinones, alkoxyphenols,dialkoxyphenols, phenols, anilines, amines, indanes, chromans,alkoxyanilines and heterocyclic rings. Examples of the metal complexinclude nickel complex and zinc complex. More specifically, compoundsdescribed in patents cited in Research Disclosure, Nos. 17643 (ItemsVII-I to VII-J), 15162, 18716 (page 650, left column), 36544 (page 527),307105 (page 872) and 15162, and compounds included in formulae ofrepresentative compounds and in exemplary compounds described inJP-A-62-215272 (pages 127 to 137) can be used.

Examples of the fungicide for use in the present invention includesodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide,ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one and salts thereof.The fungicide is preferably used in an amount of 0.02 to 5.00 mass % inthe ink.

The fungicide is described in detail, for example, in Bokin Bobai ZaiJiten (Dictionary of Microbicide and Fungicide), compiled by NipponBokin Bobai Gakkai Jiten Henshu Iinkai.

Examples of the rust inhibitor include acidic sulfite, sodiumthiosulfate, ammonium thioglycolate, diisopropylammonium nitrite,pentaerythritol tetranitrate, dicyclohexylammonium nitrite andbenzotriazole. The rust inhibitor is preferably used in an amount of0.02 to 5.00 mass % in the ink.

The pH adjusting agent for use in the present invention can be suitablyused for adjusting the pH and imparting dispersion stability. The pH ofthe ink is preferably adjusted to 8 to 11 at 25° C. If the pH is lessthan 8, the solubility of dye decreases to readily cause clogging of anozzle, whereas if it exceeds 11, the water resistance tends todeteriorate. Examples of the pH adjusting agent include organic basesand inorganic alkalis for giving a basic pH, and organic acids andinorganic acids for giving an acidic pH.

Examples of the organic base include triethanolamine, diethanolamine,N-methyldiethanolamine and dimethylethanolamine. Examples of theinorganic alkali include alkali metal hydroxides (e.g., sodiumhydroxide, lithium hydroxide, potassium hydroxide), alkali metalcarbonates (e.g., sodium carbonate, sodium hydrogencarbonate) andammonium. Examples of the organic acid include an acetic acid, apropionic acid, a trifluoroacetic acid and an alkylsulfonic acid.Examples of the inorganic acid include a hydrochloric acid, a sulfuricacid and a phosphoric acid.

In the present invention, apart from the above-described surfactants, anonionic, cationic or anionic surfactant is used as the surface tensionadjusting agent. Examples thereof include anionic surfactants such asfatty acid salt, alkylsulfuric ester salt, alkylbenzenesulfonate,alkylnaphthalenesulfonate, dialkylsulfosuccinate, alkylphosphoric estersalt, naphthalenesulfonic acid formalin condensate andpolyoxyethylenealkylsulfuric ester salt, and nonionic surfactants suchas polyoxyethylene alkyl ether, polyoxyethylene alkylallyl ether,polyoxyethylene fatty acid ester, sorbitan fatty acid ester,polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine,glycerin fatty acid ester and oxyethylene oxypropylene block copolymer.Also, SURFYNOLS (produced by Air Products & Chemicals), which are anacetylene-base polyoxyethylene oxide surfactant, are preferably used.Furthermore, amine oxide-type amphoteric surfactants such asN,N-dimethyl-N-alkylamine oxide are preferred. In addition, surfactantsdescribed in JP-A-59-157636 (pages (37) to (38)) and ResearchDisclosure, No. 308119 (1989) can also be used.

The surface tension of the ink of the present invention is, with orwithout use of such a surface tension adjusting agent, preferably from20 to 60 mN/m, more preferably from 25 to 45 mN/m.

The ink of the present invention preferably has a viscosity of 30 mPa·sor less. The viscosity is more preferably adjusted to 20 mPa·s or less.For the purpose of adjusting the viscosity, a viscosity adjusting agentis sometimes used. Examples of the viscosity adjusting agent includewater-soluble polymers such as celluloses and polyvinyl alcohol, andnonionic surfactants. The viscosity adjusting agent is described indetail in Nendo Chosei Gijutsu (Viscosity Adjusting Technology), Chap.9, Gijutsu Joho Kyokai (1999), and Inkjet Printer Yo Chemicals (98Zoho)—Zairyo no Kaihatsu Doko•Tenbo Chosa— (Chemicals for Inkjet Printer(Enlarged Edition of 98)—Survey on Development Tendency•Prospect ofMaterials—), pp. 162-174, CMC (1997).

In the present invention, if desired, various cationic, anionic ornonionic surfactants described above may be used as a dispersant or adispersion stabilizer, and fluorine- or silicone-base compounds orchelating agents as represented by EDTA may be used as a defoamingagent.

The recording paper and recording film for use in the image recordingmethod of the present invention are described below. The support whichcan be used for the recording paper or film is produced, for example,from a chemical pulp such as LBKP and NBKP, a mechanical pulp such asGP, PGW, RMP, TMP, CTMP, CMP and CGP, or a waste paper pulp such as DIP,by mixing, if desired, conventionally known additives such as pigment,binder, sizing agent, fixing agent, cation agent and paper strengthincreasing agent, and then sheeting the mixture by using various devicessuch as Fourdrinier paper machine and cylinder paper machine. Other thanthese supports, synthetic paper or plastic film sheet may be used. Thethickness of the support is preferably from 10 to 250 μm and the basisweight is preferably from 10 to 250 g/m².

An image-receiving layer and a backcoat layer may be provided on thesupport as it is to produce an image-receiving material, or afterproviding a size press or an anchor coat layer by using starch,polyvinyl alcohol or the like, an image-receiving layer and a backcoatlayer may be provided to produce an image-receiving material. Thesupport may be further subjected to a flattening treatment by acalendering device such as machine calender, TG calender and softcalender.

In the present invention, the support is preferably paper or plasticfilm of which both surfaces are laminated with polyolefin (for example,polyethylene, polystyrene, polybutene or a copolymer thereof) orpolyethylene terephthalate. In the polyolefin, a white pigment (forexample, titanium oxide or zinc oxide) or a tinting dye (for example,cobalt blue, ultramarine or neodymium oxide) is preferably added.

The image-receiving layer provided on the support contains a porousmaterial and an aqueous binder. Also, the image-receiving layerpreferably contains a pigment and the pigment is preferably a whitepigment. Examples of the white pigment include inorganic white pigmentssuch as calcium carbonate, kaolin, talc, clay, diatomaceous earth,synthetic amorphous silica, aluminum silicate, magnesium silicate,calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite,barium sulfate, calcium sulfate, titanium dioxide, zinc sulfide and zinccarbonate, and organic pigments such as styrene-base pigment, acryl-basepigment, urea resin and melamine resin. Among these, porous inorganicwhite pigments are preferred, and synthetic amorphous silica and thelike having a large pore area are more preferred. The syntheticamorphous silica may be either a silicic acid anhydride obtained by adry production process (gas phase process) or a silicic acid hydrateobtained by a wet production process.

Specific examples of the recording paper containing the pigment in theimage-receiving layer, which can be used, include those disclosed inJP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601,JP-A-10-348409, JP-A-2001-138621, JP-A-2000-43401, JP-A-2000-211235,JP-A-2000-309157, JP-A-2001-96897, JP-A-2001-138627, JP-A-11-91242,JP-A-8-2087, JP-A-8-2090, JP-A-8-2091, JP-A-8-2093, JP-A-8-174992,JP-A-11-192777 and JP-A-2001-301314.

Examples of the aqueous binder contained in the image-receiving layerinclude water-soluble polymers such as polyvinyl alcohol,silanol-modified polyvinyl alcohol, starch, cationized starch, casein,gelatin, carboxymethyl cellulose, hydroxyethyl cellulose,polyvinylpyrrolidone, polyalkylene oxide and polyalkylene oxidederivative, and water-dispersible polymers such as styrene butadienelatex and acryl emulsion. These aqueous binders can be used individuallyor in combination of two or more thereof. Among these, polyvinyl alcoholand silanol-modified polyvinyl alcohol are preferred in the presentinvention in view of adhesion to the pigment and peeling resistance ofthe image-receiving layer.

The image-receiving layer may contain a mordant, a water-proofing agent,a light fastness enhancer, a gas resistance enhancer, a surfactant, ahardening agent and other additives in addition to the pigment andaqueous binder.

The mordant added to the image-receiving layer is preferably immobilizedand for this purpose, a polymer mordant is preferably used.

The polymer mordant is described in JP-A-48-28325, JP-A-54-74430,JP-A-54-124726, JP-A-55-22766, JP-A-55-142339, JP-A-60-23850,JP-A-60-23851, JP-A-60-23852, JP-A-60-23853, JP-A-60-57836,JP-A-60-60643, JP-A-60-118834, JP-A-60-122940, JP-A-60-122941,JP-A-60-122942, JP-A-60-235134, JP-A-1-161236 and U.S. Pat. Nos.2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386,4,193,800, 4,273,853, 4,282,305 and 4,450,224. An image-receivingmaterial containing the polymer mordant described in JP-A-1-161236(pages 212 to 215) is particularly preferred. When the polymer mordantdescribed in this patent publication is used, an image having excellentimage quality can be obtained and at the same time, the light fastnessof the image is improved.

The water-proofing agent is effective for obtaining a water-resistantimage. The water-proofing agent is preferably a cationic resin. Examplesof the cationic resin include polyamidopolyamine epichlorohydrin,polyethyleneimine, polyaminesulfone, poly-dimethyldiallylammoniumchloride and cation polyacrylamide. The content of the cationic resin ispreferably from 1 to 15 mass %, more preferably from 3 to 10 mass %,based on the entire solid content of the ink-receiving layer.

Examples of the light fastness enhancer and the gas resistance enhancerinclude phenol compounds, hindered phenol compounds, thioethercompounds, thiourea compounds, thiocyanic acid compounds, aminecompounds, hindered amine compounds, TEMPO compounds, hydrazinecompounds, hydrazide compounds, amidine compounds, vinylgroup-containing compounds, ester compounds, amide compounds, ethercompounds, alcohol compounds, sulfinic acid compounds, saccharides,water-soluble reducing compounds, organic acids, inorganic acids,hydroxy group-containing organic acids, benzotriazole compounds,benzophenone compounds, triazine compounds, heterocyclic compounds,water-soluble metal salts, organic metal compounds and metal complexes.

Specific examples of these compounds include those described inJP-A-10-182621, JP-A-2001-260519, JP-A-2000-260519, JP-B-4-34953,JP-B-4-34513, JP-B-4-34512, JP-A-11-170686, JP-A-60-67190,JP-A-7-276808, JP-A-2000-94829, JP-T-8-512258 and JP-A-11-321090.

The surfactant functions as a coating aid, a releasability improver, aslipperiness improver or an antistatic agent. The surfactant isdescribed in JP-A-62-173463 and JP-A-62-183457.

Instead of the surfactant, an organic fluoro compound may be used. Theorganic fluoro compound is preferably hydrophobic. Examples of theorganic fluoro compound include fluorine-containing surfactants, oilyfluorine-base compounds (for example, fluorine oil) and solid fluorinecompound resins (for example, ethylene tetrafluoride resin) The organicfluoro compound is described in JP-B-57-9053 (columns 8 to 17),JP-A-61-20994 and JP-A-62-135826.

As the hardening agent, for example, the materials described inJP-A-1-161236 (page 222), JP-A-9-263036, JP-A-10-119423 andJP-A-2001-310547 can be used.

Other examples of the additive added to the image-receiving layerinclude a pigment dispersant, a thickener, a defoaming agent, a dye, afluorescent brightening agent, an antiseptic, a pH adjusting agent, amatting agent and a hardening agent. The image-receiving layer may becomposed of one layer or two layers.

In the recording paper or film, a backcoat layer may also be provided.Examples of the component which can be added to this layer include awhite pigment, an aqueous binder and other components.

Examples of the white pigment contained in the backcoat layer includeinorganic white pigments such as precipitated calcium carbonate, heavycalcium carbonate, kaolin, talc, calcium sulfate, barium sulfate,titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white,aluminum silicate, diatomaceous earth, calcium silicate, magnesiumsilicate, synthetic amorphous silica, colloidal silica, colloidalalumina, pseudo-boehmite, aluminum hydroxide, alumina, lithopone,zeolite, hydrolyzed halloysite, magnesium carbonate and magnesiumhydroxide, and organic pigments such as styrene-base plastic pigment,acryl-base plastic pigment, polyethylene, microcapsule, urea resin andmelamine resin.

Examples of the aqueous binder contained in the backcoat layer includewater-soluble polymers such as styrene/maleate copolymer,styrene/acrylate copolymer, polyvinyl alcohol, silanol-modifiedpolyvinyl alcohol, starch, cationized starch, casein, gelatin,carboxymethyl cellulose, hydroxyethyl cellulose andpolyvinylpyrrolidone, and water-dispersible polymers such as styrenebutadiene latex and acryl emulsion. Other examples of the componentcontained in the backcoat layer include a defoaming agent, a foaminhibitor, a dye, a fluorescent brightening agent, an antiseptic and awater-proofing agent.

In a constituent layer (including the back layer) of the inkjetrecording paper or film, a polymer fine particle dispersion may beadded. The polymer fine particle dispersion is used for the purpose ofimproving film properties, for example, stabilizing the dimension andpreventing the curling, adhesion or film cracking. The polymer fineparticle dispersion is described in JP-A-62-245258, JP-A-62-1316648 andJP-A-62-110066. When a polymer fine particle dispersion having a lowglass transition temperature (40° C. or less) is added to a layercontaining a mordant, the layer can be prevented from cracking orcurling. The curling can be prevented also by adding a polymer fineparticle dispersion having a high glass transition temperature to theback layer.

The present invention is not limited in the inkjet recording system andis used for a known system, for example, an electric charge controllingsystem of jetting out the ink by utilizing the electrostatic inductionforce, a drop-on-demand system (pressure pulse system) utilizing anoscillation pressure of a piezoelectric element, an acoustic inkjetsystem of converting electric signals into acoustic beams, irradiatingthe beams on the ink and jetting out the ink by utilizing the radiationpressure, and a thermal inkjet (bubble jet) system of heating the ink toform a bubble and utilizing the pressure generated.

The inkjet recording system includes a system of ejecting a large numberof small-volume ink droplets of a so-called photo ink having a lowconcentration, a system of improving the image quality by using aplurality of inks having substantially the same color hue but differingin the concentration, and a system using a colorless transparent ink.

The inkjet recording ink of the present invention can also be used foruses other than the inkjet recording, such as a material for displayimage, an image-forming material for interior decoration, and animage-forming material for outdoor decoration.

The material for display image indicates various materials such asposter, wallpaper, ornamental goods (e.g., ornament, doll), handbill forcommercial advertisement, wrapping paper, wrapping material, paper bag,vinyl bag, package material, billboard, image drawn on or attached tothe side face of traffic (e.g., automobile, bus, electric car), andclothing with a logo.

In the case of using the dye of the present invention as a material forforming a display image, the image includes not only a strict image butalso all patterns by a dye, which can be acknowledged by a human, suchas abstract design, letter and geometrical pattern.

The material for interior decoration indicates various materials such aswallpaper, ornamental goods (e.g., ornament, doll), luminaire member,furniture member and design member of floor or ceiling. In the case ofusing the dye of the present invention as a material for forming animage, the image includes not only a strict image but also all patternsby a dye, which can be acknowledged by a human, such as abstract design,letter and geometrical pattern.

The material for outdoor decoration indicates various materials such aswall material, roofing material, billboard, gardening material, outdoorornamental goods (e.g., ornament, doll) and outdoor luminaire member. Inthe case of using the dye of the present invention as a material forforming an image, the image includes not only a strict image but alsoall patterns by a dye, which can be acknowledged by a human, such asabstract design, letter and geometrical pattern.

In these uses, examples of the medium on which the pattern is formedinclude various materials such as paper, fiber, cloth (includingnon-woven fabric), plastic, metal and ceramic. Examples of the dyeingform include mordanting, printing and fixing of a dye in the form of areactive dye having introduced thereinto a reactive group. Among these,preferred is dyeing by mordanting.

EXAMPLES

The present invention is described below by referring to Examples,however, the present invention is not limited thereto.

(Ink Containing at Least One Organic Solvent Having a Boiling Point of150° C. or More and at Least One Organic Solvent Having a Boiling Pointof Less than 150° C.)

Example 1

Deionized water was added to the following components to make 1 literand the resulting solution was stirred for 1 hour under heating at 30 to40° C. and then filtered under reduced pressure through a microfilterhaving an average pore size of 0.25 μm to prepare a light cyan inksolution (LC-101)

[Formulation of Light Cyan Ink LC-101] (Solid Contents) Cyan Dye (154)of the present invention 17.5 g/liter  Benzotriazole (BTZ) 0.08 g/liter PROXEL XL2  3.5 g/liter (Liquid Components) Diethylene glycol (DEG) 150g/liter Glycerin (GR) 130 g/liter Triethylene glycol monobutyl ether(TGB) 130 g/liter Triethanolamine (TEA)  6.9 g/liter Surfynol STG (SW) 10 g/liter

Inks LC-102 to LC-106 were prepared by changing the solvent species ofLC-101 as shown in Table 1 below. TABLE 1 LC-101 LC-102 LC-103 LC-104LC-105 LC-106 (154) 17.5 g 17.5 g 17.5 g 17.5 g 17.5 g 17.5 g BTZ 0.08 g0.08 g 0.08 g 0.08 g 0.08 g 0.08 g PROXEL 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g3.5 g DEG 150 g — 150 g 50 g 50 g 50 g GR 130 g 150 g 100 g 100 g 100 g100 g TGB 130 g 130 g 150 g 50 g 50 g 50 g TEA 6.9 g 6.9 g 6.9 g 6.9 g6.9 g 6.9 g SW 10 g 10 g 10 g 10 g 10 g 10 g PRD — 90 g 10 g 10 g 10 g10 g IPA — — — 150 g — — MFG — — — — 150 g — MS — — — — — 150 g Finished1 liter 1 liter 1 liter 1 liter 1 liter 1 liter amount**All were made to a finished amount of 1 liter by adding water.PRD: 2-PyrrolidoneIPA: 2-PropanolMFG: 1-Methoxy-2-propanolMS: 2-Methoxyethanol

Also, Cyan Ink Solution C-101 was prepared by increasing Cyan Dye (154)to 68 g in the formulation above.

[Formulation of Cyan Ink C-101] (Solid Contents) Cyan Dye (154) of thepresent invention  68 g/liter Benzotriazole (BTZ) 0.08 g/liter  PROXELXL2  3.5 g/liter (Liquid Components) Diethylene glycol 150 g/literGlycerin 130 g/liter Triethylene glycol monobutyl ether 130 g/literTriethanolamine  6.9 g/liter Surfynol STG  10 g/liter

Cyan Inks C-102 to C-106 were prepared by changing the ink formulationof C-101 as shown in Table 2 below. TABLE 2 C-101 C-102 C-103 C-104C-105 C-106 (154) 68 g 68 g 68 g 68 g 68 g 68 g BTZ 0.08 g 0.08 g 0.08 g0.08 g 0.08 g 0.08 g PROXEL 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g DEG 150g — 150 g 50 g 50 g 50 g GR 130 g 150 g 100 g 70 g 70 g 70 g TGB 130 g100 g 150 g 20 g 20 g 20 g TEA 6.9 g 6.9 g 6.9 g 6.9 g 6.9 g 6.9 g SW 10g 10 g 10 g 10 g 10 g 10 g PRD — 100 g 10 g 10 g 10 g 10 g IPA — — — 180g — — MFG — — — — 180 g — MS — — — — — 180 g Finished 1 liter 1 liter 1liter 1 liter 1 liter 1 liter amount**All were made to a finished amount of 1 liter by adding water.

These inks each was filled in a cyan ink-light cyan ink cartridge ofInkjet Printer PM-950C manufactured by Seiko Epson Corporation and byusing the inks of PM-950C for other colors, a cyan monochromatic imagewas printed. The image was printed on inkjet paper Photo Gloss Paper EXproduced by Fuji Photo Film Co., Ltd. used as the image-receiving sheetand evaluated on the ejection stability of ink and the image fastness.

(Evaluation Test)

1) As for the ejection stability, cartridges were set in the printer andafter confirming the ejection of ink from all nozzles, the image wasoutput on 20 sheets of A4-size paper and rated based on the followingcriteria:

A: Printing was not disordered from the start to the end of printing.

B: Printing was disordered in some outputs.

C: Printing was disordered from the start to the end of printing.

2) As for the image preservability, a cyan solid image printed samplewas prepared and subjected to the following evaluations.

(1) In the evaluation of light fastness, the image density Ciimmediately after printing was measured by a reflection densitometerX-Rite 310 and after the image was irradiated with xenon light (85,000lx) for 10 days by using a weather meter manufactured by Atlas, theimage density Cf was again measured. Then, the dye residual ratioCf/Ci×100 was determined and evaluated. The dye residual ratio wasevaluated at three points having a reflection density of 1, 1.5 and 2.The sample was rated A when the dye residual ratio was 70% or more atany density, rated B when less than 70% at two points, and rated C whenless than 70% at all points.

(2) In the evaluation of heat fastness, the density was measured byX-Rite 310 before and after the sample was stored for 10 days under theconditions of 80° C. and 15% RH, and the dye residual ratio wasdetermined and evaluated. The dye residual ratio was evaluated at threepoints having a reflection density of 1, 1.5 and 2. The sample was ratedA when the dye residual ratio was 90% or more at any density, rated Bwhen less than 90% at two points, and rated C when less than 90% at allpoints.

(3) In the evaluation of ozone resistance, the photo gloss paper havingformed thereon an image was left standing for 7 days in a box set to anozone gas concentration of 0.5 ppm and the image density before andafter standing in the ozone gas atmosphere was measured by a reflectiondensitometer (X-Rite 310TR) and evaluated as the dye residual ratio. Thedye residual ratio was measured at three points having a reflectiondensity of 1, 1.5 and 2.0. The ozone gas concentration in the box wasset by using an ozone gas monitor (Model OZG-EM-01) manufactured byAPPLICS.

The sample was rated on a scale of three stages, namely, rated A whenthe dye residual ratio was 80% or more at any density, rated B when lessthan 80% at one or two point(s), and rated C when less than 70% at allpoints.

3) As for the blurring of the image under high-humidity condition, aprinting pattern where four cyan square patterns each in a size of 3cm×3 cm were arrayed to form a two-line and two-column table shape witha 1-mm white clearance between respective square patterns was preparedand after this image sample was stored under conditions of 25° C. and90% RH for 72 hours, the bleeding of cyan dye in the white clearance wasobserved. The sample was rated A when the increase of cyan density inthe white clearance based on the density immediately after printing wasless than 0.01 as measured by a cyan filter of Status A, rated B whenfrom 0.01 to 0.05, and rated C when more than 0.05.

The results obtained are shown in Table 3 below. TABLE 3 Ejection LightHeat O₃ C Stability Fastness Fastness Resistance Bleeding Genuine ink ofA C B C B EPSON (PM-950) LC-101, C-101 A A A A C (Reference Example)LC-102, C-102 A A A A C (Reference Example) LC-103, C-103 A A A A C(Reference Example) LC-104, C-104 A A A A A (Invention) LC-105, C-105 AA A A A (Invention) LC-106, C-106 A A A A A (Invention)

As seen from the results in the Table, the systems using the ink set ofthe present invention containing both an organic solvent having aboiling point of 150° C. or more and an organic solvent having a boilingpoint of less than 150° C. were decreased in the bleeding as comparedwith Reference Examples not containing these organic solvents at thesame time, and also surpassed the genuine ink of EPSON in view of boththe fastness of image and the blurring of image.

(Ink Containing a Water-Miscible Organic Solvent which is a Mixture ofTwo or More Members where at Least One Member Contains a PolyhydricAlcohol and/or a Derivative Thereof, at a Concentration of 10 to 60(Mass/Volume) %)

Example 2

Deionized water was added to the following components to make 1 literand the resulting solution was stirred for 1 hour under heating at 30 to40° C. and after adjusting the pH to 9 with 10 mol/liter of KOH,filtered under reduced pressure through a microfilter having an averagepore size of 0.25 μm to prepare a light cyan ink solution. Cyan dye(Compound 154) of the present 17.5 g/liter  invention Diethylene glycol164 g/liter Glycerin 123 g/liter Triethylene glycol monobutyl ether 119g/liter Triethanolamine  6.5 g/liter Benzotriazole 0.07 g/liter  PROXELXL2  3.5 g/liter Surfactant (w-1)  10 g/liter

Furthermore, a cyan ink, a light magenta ink, a magenta ink, a yellowink, a dark yellow ink and a black ink were prepared by changing the dyespecies and the additives, and Ink Set 101 shown in Table 4 below wasprepared. TABLE 4 Light Light Dark Cyan Cyan Magenta Magenta YellowYellow Black Dye (g/liter) 154 154 A-1 A-1 A-3 A-3 A-5 17.5 68.0 10.230.8 14.0 10.0 20.0 A-4 A-4 A-6 14.0 10.0 39.0 A-2 A-7 13.0 17.0 A-320.0 Diethylene glycol 167 110 47 76 85 — 20 (g/liter) Urea (g/liter) —— 37 46 — — — Glycerin (g/liter) 164 148 198 150 154 147 120 Triethyleneglycol 125 132 105 107 130 127 — monobutyl ether (g/liter) Diethyleneglycol — — — — — — 230 monobutyl ether (g/liter) 2-Pyrrolidone — 20 40 —— — 80 (g/liter) Surfactant (g/liter) 10 10 6 12 3 3 5 Triethanolamine6.5 10 7 7 1 1 18 (g/liter) Benzotriazole 0.07 0.09 0.07 0.08 0.06 0.080.08 (g/liter) Proxel XL2 (g/liter) 1.0 4.0 5.0 4.5 3 5 4 Concentrationof 46.25 42.0 39.7 34.0 37.0 27.5 46.8 water-miscible organic solvent,(mass/volume) %Deionized water was added to make 1 liter.

Ink Sets 102 to 110 were prepared by changing the dye species for lightcyan ink and cyan ink and the concentration of water-miscible organicsolvent in Ink Set 101 as shown in Table 5 below. The concentration ofthe water-miscible organic solvent was set by appropriately adjustingthe amounts added of diethylene glycol, glycerin, triethylene glycolmonobutyl ether, diethylene glycol monobutyl ether, 2-pyrrolidone andtriethanolamine. TABLE 5 Presence or Absence of Light Ink Set PolyhydricAlcohol Cyan (%) Cyan (%) Remarks 101 dye present 154 154 Inventionconcentration of water- 46.25 42.0 miscible organic solvent 102 dyepresent 154 154 Invention concentration of water- 20.0 42.0 miscibleorganic solvent 103 dye present 154 154 Invention concentration ofwater- 46.25 20.0 miscible organic solvent 104 dye present 154 154Invention concentration of water- 55.0 55.0 miscible organic solvent 105dye present 154 154 Invention concentration of water- 20.0 20.0 miscibleorganic solvent 106 dye present 154 154 Reference concentration ofwater- 5.0 42.0 miscible organic solvent 107 dye present 154 154Reference concentration of water- 5.0 5.0 miscible organic solvent 108dye present 154 154 Reference concentration of water- 70.0 70.0 miscibleorganic solvent 109 dye none 154 154 Reference concentration of water-46.25 42.0 miscible organic solvent 110 dye present A-2 A-2 Comparisonconcentration of water- 46.25 42.0 miscible organic solvent

These ink sets 101 to 110 each was filled in cartridges of InkjetPrinter PM800C (manufactured by Seiko Epson Corporation) and an imagewas printed by this printer on inkjet paper Photo Gloss Paper EXproduced by Fuji Photo Film Co., Ltd. and subjected to the followingevaluations.

The “printing performance (1)” was evaluated in the same manner as theejection stability of Example 1. The evaluation criteria were also thesame as in Example 1.

As for the “printing performance (2)”, the cartridge was left standingat 60° C. for 2 days and thereafter, the disorder of printing wasevaluated in the same manner as in the printing performance (1).

As for the “drying property”, the image was touched with a fingerimmediately after printing and the staining was evaluated with an eye.

As for the fineline blurring, yellow, magenta, cyan and black finelinepatterns were printed and the “fineline blurring (1)” was evaluated withan eye. In the case of black, the magenta ink was solid-printed, thenfinelines of black were printed, and the “fineline blurring (2)” due tocontact of two colors was evaluated.

As for the “water resistance”, the obtained image was immersed indeionized water for 10 seconds and then the blurring of image wasevaluated.

As for the image preservability, a cyan solid image printed sample wasprepared and subjected to the following evaluations.

In the evaluation of “light fastness”, the image density Ci immediatelyafter printing was measured by a reflection densitometer (X-Rite 310TR)and after the image was irradiated with xenon light (85,000 lx) for 7days by using a weather meter manufactured by Atlas, the image densityCf was again measured. Then, the dye residual ratio Ci/Cf*100 wasdetermined and evaluated. The dye residual ratio was evaluated at threepoints having a reflection density of 1, 1.5 and 2. The sample was ratedA when the dye residual ratio was 85% or more at any density, rated Bwhen less than 85% at two points, and rated C when less than 85% at allpoints.

In the evaluation of “heat fastness”, the density was measured by areflection densitometer (X-Rite 310TR) before and after the sample wasstored for 7 days under the conditions of 70 to 80% RH and the dyeresidual ratio was determined and evaluated. The dye residual ratio wasevaluated at three points having a reflection density of 1, 1.5 and 2.The sample was rated A when the dye residual ratio was 90% or more atany density, rated B when less than 90% at two points, and rated C whenless than 90% at all points.

In the evaluation of “ozone resistance”, the density was measured by areflection densitometer (X-Rite 310TR) before and after the sample wasstored for 7 days under the conditions of ventilation and heating at 80°C. and the dye residual ratio was determined and evaluated. The dyeresidual ratio was evaluated at three points having a reflection densityof 1, 1.5 and 2. The sample was rated A when the dye residual ratio was90% or more at any density, rated B when less than 90% at two points,and rated C when less than 90% at all points.

The results obtained are shown in Tables 6 and 7 below. TABLE 6 PrintingPrinting Drying Fineline Fineline Water Ink Performance PerformanceProp- Blurring Blurring Resis- Set 1 2 erty 1 2 tance 101 A A ◯ ◯ ◯ ◯102 A A ◯ ◯ ◯ ◯ 103 A A ◯ ◯ ◯ ◯ 104 A A ◯ ◯ ◯ ◯ 105 A A ◯ ◯ ◯ ◯ 106 B C◯ ◯ ◯ ◯ 107 B C ◯ ◯ ◯ ◯ 108 B B X ◯ ◯ X 109 C C ◯ ◯ ◯ ◯ 110 A B ◯ ◯ ◯ ◯

TABLE 7 Light Heat Gas Ink Set Fastness Fastness Resistance Remarks 101A A A Invention 102 A A A Invention 103 A A A Invention 104 A A AInvention 105 A A A Invention 106 A A A Reference 107 A A A Reference108 A B B Reference 109 A A A Reference 110 B B C Comparison

It is seen that the ink of the present invention is excellent in theprinting performances (1) and (2) and therefore, reveals excellentejection stability and also that excellent performance is exhibitedregarding water resistance and fastness to light and heat. Furthermore,the ink of the present invention is excellent in the performance at thefineline output and free from fineline

Incidentally, even when the image-receiving paper used in the presentinvention was changed to PM Photographic Paper produced by Seiko EpsonCorporation or PR101 produced by Canon Inc., the same effects as in theresults above were obtained.

Example 3

The same inks as prepared in Example 2 were filled in cartridges ofInkjet Printer BJ-F850 (manufactured by Canon Inc.) and an image wasprinted by this printer on inkjet paper Photo Gloss Paper EX produced byFuji Photo Film Co., Ltd. and evaluated in the same manner as in Example2. Then, the same results as in Example 2 were obtained. Even when theimage-receiving paper was changed to PM Photographic Paper produced bySeiko Epson Corporation or PR101 produced by Canon Inc., the sameeffects were obtained.

Example 4

Dye (Compound 189) (7 g) and 4 g of sodium dioctylsulfosuccinate weredissolved in 6 g of High Boiling Point Organic Solvent (s-1), 10 g ofHigh Boiling Point Organic Solvent (s-2) and 50 ml of ethyl acetate at70° C. To the resulting solution, 500 ml of deionized water was addedwhile stirring with magnetic stirrer to produce an oil-in-water typecoarse particle dispersion.

This coarse particle dispersion was passed 5 times throughMicrofluidizer (manufactured by Microfluidex Inc.) under a pressure of60 MPa, thereby performing the pulverization. From the finishedemulsified product, the solvent was removed by a rotary evaporator untilthe odor of ethyl acetate was not generated.

To the thus-obtained finely emulsified product of oil-soluble dye, 140 gof diethylene glycol, 64 g of glycerin, 13 g of Surfactant (w-1) andadditives such as urea were added. Thereafter, 900 ml of deionized waterwas added, the pH was adjusted to 9 with 10 mol/liter of KOH and theconcentration of water-miscible organic solvent was adjusted to producea light cyan ink shown in Table 8 below. The volume average particlesize of the resulting emulsion-dispersed ink was measured by usingMicrotrac UPA (manufactured by Nikkiso K.K.) and found to be 58 nm.

Also, the magenta ink, light magenta ink, cyan ink, yellow ink, darkyellow ink and black ink of Ink Set 201 shown in Table 8 below wereprepared by changing the dye species and high boiling point organicsolvents used. TABLE 8 Light Light Dark Cyan Cyan Magenta Magenta YellowYellow Black Dye (g/liter) C-1 7.0 C-1 35.0 a-3 6.0 a-3 20.0 Y-1 28.0Y-1 10.0 C-1 19.0 C-1 10.0 M-1 10.0 Y-1 14.0 High Boiling S-1 6.0 25.04.0 14.0 20.0 20.0 30.0 Point Organic S-2 10.0 45.0 6.0 25.0 35.0 35.053.0 Solvent (g/liter) Sodium dioctyl- 4.0 30.0 6.2 23.0 35.0 35.0 52.0sulfosuccinate (g/liter) Diethylene glycol 140 140 130 140 130 130 120(g/liter) Urea (g/liter) 46.0 46.0 46.0 46.0 46.0 46.0 46.0 Glycerin64.0 64.0 64.0 64.0 64.0 64.0 64.0 (g/liter) Triethanolamine 10 10 10 1010 10 10 (g/liter) Benzotriazole 0.08 0.08 0.08 0.08 0.08 0.08 008(g/liter) Surfactant W-1 13 13 13 13 13 13 13 (g/liter) Proxel XL2 3.53.5 3.5 3.5 3.5 3.5 3.5 (g/liter) Concentration of 21.4 21.4 20.4 21.420.4 20.4 19.4 water-miscible organic solvent (%) Deionized water wasadded to make 1 liter. Volume average 58 nm 65 nm 60 nm 55 nm 60 nm 58nm 70 nm particle size

Also, Ink Sets 202 to 209 were prepared in the same manner as shown inTable 9 below.

Furthermore, Ink Set 210 for comparison was prepared according to thesame formulation as Ink Set 201 except for changing the dye species toC-1. These Ink Sets 201 to 210 each was filled in cartridges of InkjetPrinter PM770C (manufactured by Seiko Epson Corporation) and an imagewas printed by this printer on inkjet paper Photo Gloss Paper EXproduced by Fuji Photo Film Co., Ltd. and subjected to the sameevaluations as in Example 2. The results obtained are shown in Table 9below. TABLE 9 Concentration Presence of Water- or Absence Miscible ofEjection Fineline Fineline Ink Organic Polyhydric Stability Light HeatOzone Water Blurring Blurring Set Dye Solvent (%) Alcohol (1) FastnessFastness Resistance Resistance (1) (2) Remarks 201 189 20 present A A AA A ◯ ◯ Invention 202 189 30 present A A A A A ◯ ◯ Invention 203 189 40present A A A A A ◯ ◯ Invention 204 182 30 present A A A A A ◯ ◯Invention 205 180 40 present A A A A A ◯ ◯ Invention 206 187 50 presentA A A A A ◯ ◯ Invention 207 189 5 present B A A A A ◯ ◯ Reference 208189 70 present C A A A A ◯ ◯ Reference 209 189 30 none C A A B A ◯ ◯Reference 210 C-1 30 present A A A B A ◯ ◯ Comparison

It is seen that the ink of the present invention is excellent in all ofejection stability, weather resistance (light fastness, heat fastnessand ozone resistance) and water resistance and can give a recorded imagefree from fineline blurring. The color hue obtained by the inks (201 to206) of the present invention was good and equal to that of ink (210).

(Ink Containing a Water-Miscible Organic Solvent in which the Dye has aSolubility of 10 (g/100 g-Solvent) or More at 25° C., to a Content of 10Mass % or Less in the Ink)

Example 5

Deionized water was added to the following components to make 1 literand the resulting solution was stirred for 1 hour under heating at 30 to40° C. and then filtered under reduced pressure through a microfilterhaving an average pore size of 0.25 μm to prepare a light cyan inksolution (LC-101)

[Formulation of Light Cyan Ink LC-101] (Solid Contents) Cyan Dye (154)of the present invention 17.5 g/liter  Benzotriazole (BTZ) 0.08 g/liter PROXEL XL2  3.5 g/liter (Liquid Components) Diethylene glycol (DEG) 150g/liter Glycerin (GR) 130 g/liter Triethylene glycol monobutyl ether(TGB) 130 g/liter Triethanolamine (TEA)  6.9 g/liter Surfynol STG (SW) 10 g/liter

Inks LC-102 to LC-106 were prepared by changing the solvent species ofLC-101 as shown in Table 10 below. TABLE 10 LC-101 LC-102 LC-103 LC-104LC-105 LC-106 (154) 17.5 g 17.5 g 17.5 g 17.5 g 17.5 g 17.5 g BTZ 0.08 g0.08 g 0.08 g 0.08 g 0.08 g 0.08 g PROXEL 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g3.5 g DEG 150 g 150 g 150 g 150 g 150 g 100 g GR 130 g 130 g 130 g 130 g130 g 120 g TGB 130 g — 80 g — 40 g 20 g DGB — — — 150 g 100 g — DGE —150 g 80 g 6.9 g 6.9 g 6.9 g MFG — — — — 100 g 250 g TEA 6.9 g 6.9 g 6.9g 6.9 g 6.9 g 6.9 g SW 10 g 10 g 10 g 10 g 10 g 10 g Finished 1 liter 1liter 1 liter 1 liter 1 liter 1 liter amount* D** 13.7 15.7 16.7 0.7 4.72.7*All were made to a finished amount of 1 liter by adding water.**The concentration (mass %) of solvent in which Dye (154) has asolubility of 10 g/100 g-solvent or more at 25° C.DGB: Diethylene glycol monobutyl etherDGE: Diethylene glycol monoethyl etherMFG: 1-Methoxy-2-propanolSolvent in which Dye (154) has a solubility of 10 g/100 g-solvent ormore at 25° C.:

Three solvents, that is, TGB, DGE and TEA.

Also, Cyan Ink Solution C-101 was prepared by increasing Cyan Dye (154)to 68 g in the formulation above.

[Formulation of Cyan Ink C-101] (Solid Contents) Cyan Dye (154) of thepresent invention  68 g/liter Benzotriazole (BTZ) 0.08 g/liter  PROXELXL2  3.5 g/liter (Liquid Components) Diethylene glycol 150 g/literGlycerin 130 g/liter Triethylene glycol monobutyl ether 130 g/literTriethanolamine  6.9 g/liter Surfynol STG  10 g/liter

Cyan Inks C-102 to C-106 were prepared by changing the ink formulationof C-101 as shown in Table 11 below. TABLE 11 C-101 C-102 C-103 C-104C-105 C-106 (154) 68 g 68 g 68 g 68 g 68 g 68 g BTZ 0.08 g 0.08 g 0.08 g0.08 g 0.08 g 0.08 g PROXEL 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g DEG 150g 150 g 150 g 150 g 150 g 100 g GR 130 g 130 g 130 g 130 g 130 g 120 gTGB 130 g — 80 g — 40 g 20 g DGB — — — 150 g 100 g — DGE — 150 g 80 g6.9 g 6.9 g 6.9 g MFG — — — — 100 g 250 g TEA 6.9 g 6.9 g 6.9 g 6.9 g6.9 g 6.9 g SW 10 g 10 g 10 g 10 g 10 g 10 g Finished 1 liter 1 liter 1liter 1 liter 1 liter 1 liter amount* D** 13.7 15.7 16.7 0.7 4.7 2.7

These inks were evaluated on the ejection stability, image fastness andblurring of image under high-humidity condition in the same manner as inExample 1.

The results obtained are shown in Table 12 below. TABLE 12 EjectionLight Heat O₃ C Stability Fastness Fastness Resistance Bleeding Genuineink of A C B C B EPSON (PM-950) LC-101, C-101 A A A A C (ReferenceExample) LC-102, C-102 A A A A C (Reference Example) LC-103, C-103 A A AA C (Reference Example) LC-104, C-104 A A A A A (Invention) LC-105,C-105 A A A A A (Invention) LC-106, C-106 A A A A A (Invention)

As seen from the results in Table 12, the systems using the ink set ofthe present invention were decreased in the bleeding as compared withReference Examples and also surpassed the genuine ink of EPSON in viewof both the fastness of image and the blurring of image.

(Ink Containing an Organic Solvent which is Liquid at OrdinaryTemperature and does not Contain a Heteroatom Other than an Oxygen Atom)

Example 6

Deionized water was added to the following components to make 1 literand the resulting solution was stirred for 1 hour under heating at 30 to40° C. and then filtered under reduced pressure through a microfilterhaving an average pore size of 0.25 μm to prepare a light cyan inksolution (LC-101).

[Formulation of Light Cyan Ink LC-101] (Solid Contents) Cyan Dye (154)of the present invention 17.5 g/liter  PROXEL  3.5 g/liter (LiquidComponents) Diethylene glycol 120 g/liter Glycerin 100 g/literTriethylene glycol monobutyl ether 100 g/liter 2-Pyrrolidone  90 g/literTriethanolamine (TEA, pH adjusting  6.9 g/liter agent) Surfynol STG (SW,surfactant)  10 g/liter

Also, Cyan Ink Solution C-101 was prepared by increasing Cyan Dye (154)to 68 g in the formulation above.

[Formulation of Cyan Ink C-101] (Solid Contents) Cyan Dye (154) of thepresent invention  68 g/liter PROXEL  3.5 g/liter (Liquid Components)Diethylene glycol 120 g/liter Glycerin 100 g/liter Triethylene glycolmonobutyl ether 100 g/liter 2-Pyrrolidone  90 g/liter Triethanolamine(TEA, pH adjusting  6.9 g/liter agent) Surfynol STG (SW, surfactant)  10g/liter

Inks LC-102 to LC-106 and C-102 to C-106 having thoroughly the samecomposition as LC-101 and C-101 except for adding additives as shown inTables 13 and 14 below were prepared. TABLE 13 LC-101 LC-102 LC-103LC-104 LC-105 LC-106 154 17.5 g 17.5 g 17.5 g 17.5 g 17.5 g 17.5 gPROXEL 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g DEG 120 g 120 g 120 g 120 g50 g 140 g GR 100 g 100 g 100 g 100 g 100 g 100 g TGB 100 g 100 g 100 g100 g 50 g — PRD 90 g — — — — — TEA 6.9 g 6.9 g 6.9 g 6.9 g 6.9 g 6.9 gSW 10 g 10 g 10 g 10 g 10 g 10 g DMI — 90 g — — — — DMAc — — 90 g — — —MFG — — — 90 g — — DEB — — — — 90 g 130 g Finished 1 liter 1 liter 1liter 1 liter 1 liter 1 liter amount**ll were made to a finished amount of 1 liter by adding water.DMI: 1,3-DimethylimidazolidinoneDMAc: N,N-dimethylacetamideMFG: 1-Methoxy-2-propanolDEB: Diethylene glycol monobutyl ether

TABLE 13 C-101 C-102 C-103 C-104 C-105 C-106 154 23 g 23 g 23 g 23 g 23g 23 g PROXEL 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g 3.5 g DEG 120 g 120 g 120 g120 g 50 g 140 g GR 100 g 100 g 100 g 100 g 100 g 100 g TGB 100 g 100 g100 g 100 g 50 g — PRD 90 g — — — — — TEA 6.9 g 6.9 g 6.9 g 6.9 g 6.9 g6.9 g SW 10 g 10 g 10 g 10 g 10 g 10 g DMI — 90 g — — — — DMAc — — 90 g— — — MFG — — — 90 g — — DEB — — — — 90 g 130 g Finished 1 liter 1 liter1 liter 1 liter 1 liter 1 liter amount**All were made to a finished amount of 1 liter by adding water.

These inks each was filled in a cyan ink-light cyan ink cartridge ofInkjet Printer PM-950C manufactured by Seiko Epson Corporation and byusing the inks of PM-950C for other colors, a cyan monochromatic imagewas printed. The image was printed on inkjet paper Photo Gloss Paper EXproduced by Fuji Photo Film Co., Ltd. used as the image-receiving sheetand evaluated on the ejection stability of ink, the image fastness andthe blurring of image under high-humidity condition.

(Evaluation Test)

1) As for the ejection stability, cartridges were set in the printer andafter confirming the ejection of ink from all nozzles, the printer wasstored for 2 weeks under the conditions of 30° C. and 90% RH. Underthese conditions, the image was output on 20 sheets of A4-size paper andrated based on the following criteria:

A: Printing was not disordered from the start to the end of printing.

B: Printing was disordered in some outputs.

C: Printing was disordered from the start to the end of printing.

2) The image preservability was evaluated in the same manner as inExample 1.

3) The blurring of image under high-humidity condition was alsoevaluated in the same manner as in Example 1.

The results obtained are shown in Table 15 below. TABLE 15 EjectionLight Heat O₃ C Property Fastness Fastness Resistance Bleeding Genuineink of A B B C B EPSON (PM-950) LC-101, C-101 A A A A C (ReferenceExample) LC-102, C-102 A A A A C (Reference Example) LC-103, C-103 A A AA C (Reference Example) LC-104, C-104 A A A A A (Invention) LC-105,C-105 A A A A A (Invention) LC-106, C-106 A A A A A (Invention)

As seen from the results in Table 15, the systems using the ink set ofthe present invention surpassed Reference Examples in view of blurringof image and also surpassed the ink (genuine ink of PM-950C) of EPSON inview of fastness of dye.

(Ink Containing a Water-Miscible Organic Solvent Having a Vapor Pressureof 2,000 Pa or Less at 20° C.)

Example 7

(Preparation of Ink Solution)

Deionized water was added to the following components to make 1 literand the resulting solution was dissolved with stirring for 1 hour underheating at 30 to 40° C. and then filtered under reduced pressure througha microfilter having an average pore size of 0.25 μm to prepare a lightcyan ink solution. Cyan Dye [154]  17.5 g Triethylene glycol monobutylether 119.0 g Glycerin 123.0 g Diethylene glycol 164.0 g PROXEL XL2[produced by Zeneca]  1.0 g Benzotriazole  0.07 g Surfactant  10.0 g(polyethylene glycol (average number of repetitions of ethylene oxide:10) terminated with 2-butyl octanoic acid ester at one end)(Preparation of Ink Solution)

Deionized water was added to the following components to make 1 literand the resulting solution was dissolved with stirring for 1 hour underheating at 30 to 40° C. and then filtered under reduced pressure througha microfilter having an average pore size of 0.25 μm to prepare a cyanink solution. Cyan Dye [154]  68.0 g Triethylene glycol monobutyl ether127.0 g Glycerin 110.0 g Diethylene glycol 107.0 g PROXEL XL2 [producedby Zeneca]  4.0 g Benzotriazole  0.09 g Surfactant  10.0 g (polyethyleneglycol (average number of repetitions of ethylene oxide: 10) terminatedwith 2-butyl octanoic acid ester at one end)

Then, inks of Examples 8 and 9 and Comparative Examples 1 and 2 wereprepared thoroughly in the same manner as the light cyan ink and cyanink above except for changing the dye, water-miscible organic solventspecies and amount as shown in Table 16 below. TABLE 16 Vapor LightPressure Composition Cyan Cyan [Pa] Example 7 Dye (154) (154) —Diethylene glycol 164 107 <1.3 (20° C.) Glycerin 123 110   0.3 (20° C.)Triethylene glycol 119 127 <1.3 (20° C.) monobutyl ether Example 8 Dye(154) (154) — Diethylene glycol 167 110 <1.3 (20° C.) Glycerin 164 148  0.3 (20° C.) Triethylene glycol 125 132 <1.3 (20° C.) monobutyl etherExample 9 Dye (154) (154) — Diethylene glycol 164 107 <1.3 (20° C.)Glycerin 123 110   0.3 (20° C.) 1-Methoxy-2-propanol 119 127 1013 (20°C.)  Comparative Dye (C-1) (C-1) — Example 1 Diethylene glycol 164 107<1.3 (20° C.) Glycerin 123 110   0.3 (20° C.) Triethylene glycol 119 127<1.3 (20° C.) monobutyl ether Comparative Dye (154) (154) — Example 22-Propanol 226 162 4320 (20° C.)  Ethylene glycol 181 182 6400 (20° C.) dimethyl ether

The light cyan inks and cyan inks produced above each was filled in acartridge of Inkjet Printer PM920C (manufactured by Seiko EpsonCorporation) and an image was printed by this printer on inkjet paperPhoto Gloss Paper EX produced by Fuji Photo Film Co., Ltd. and subjectedto the following evaluations. The results obtained are shown in Table17.

(1) As for the ejection stability, cartridges were set in the printerand by performing a continuous ejection test of ink from nozzles, theejection stability (1) was evaluated.

Furthermore, the ejection stability (2) after the printer was leftstanding at room temperature for 2 weeks in the state that thecartridges were set in the printer was also evaluated.

◯: Stable.

Δ: Slightly unstable.

X: Unstable.

(2) As for the image preservability, a cyan solid image printed samplewas prepared and subjected to the following evaluations.

In the evaluation of light fastness, the image density Ci immediatelyafter printing was measured by a reflection densitometer (X-Rite 310TR)and after the image was irradiated with xenon light (85,000 lx) for 6days by using a weather meter manufactured by Atlas, the image densityCf was again measured. Then, the dye residual ratio (100×Cf/Ci) wasdetermined and evaluated. The dye residual ratio was evaluated at threepoints having a reflection density of 1, 1.5 and 2. The sample was ratedA when the dye residual ratio was 80% or more at any density, rated Bwhen less than 80% at two points, and rated C when less than 80% at allpoints.

In the evaluation of heat fastness, the density was measured by areflection densitometer (X-Rite 310TR) before and after the sample wasstored for 5 days under the conditions of 80° C. and 70% RH and the dyeresidual ratio was determined and evaluated. The dye residual ratio wasevaluated at three points having a reflection density of 1, 1.5 and 2.The sample was rated A when the dye residual ratio was 90% or more atany density, rated B when less than 90% at two points, and rated C whenless than 90% at all points.

The ozone resistance was evaluated in the same manner as in Example 2.

The results obtained are shown in Table 17 below. TABLE 17 EjectionEjection Stability Stability Light Heat Ozone Ink Dye (1) (2) FastnessFastness Resistance Example 7 (154) ◯ ◯ A A A Example 8 (154) ◯ ◯ A A AExample 9 (154) ◯ ◯ A A A Comparative (c-1) ◯ ◯ C A C Example 1Comparative (154) ◯ X A A A Example 2

It is seen that when the ink of the present invention is used, excellentejection stability can be obtained and excellent performance is alsoexhibited regarding the fastness.

The color hue obtained by the inks of the present invention was equal tothat of the ink of Comparative Example 1.

Also, when inks of the present invention were prepared by using otherwater-soluble dyes represented by formula (I) in place of the cyan dye(154) in this Example, the same effects as above were obtained on theweather resistance, ejection stability and color hue.

Incidentally, even when the image-receiving paper used in the presentinvention was changed to PM Photographic Paper produced by Seiko EpsonCorporation or PR101 produced by Canon Inc., the same effects as in theresults above were obtained.

(Effects of the Invention)

According to the present invention, an inkjet recording ink and aninkjet recording method are provided, in which the ink is an aqueous inkadvantageous in view of handleability, odor, safety and the like andwhere high ejection stability, good color hue and excellent fastness toweather and water can be ensured and a recorded image with high imagequality can be obtained.

INDUSTRIAL APPLICABILITY

The ink of the present invention is not limited in the inkjet recordingsystem and can be used for a known system, for example, an electriccharge controlling system of jetting out the ink by utilizing theelectrostatic induction force, a drop-on-demand system (pressure pulsesystem) utilizing an oscillation pressure of a piezoelectric element, anacoustic inkjet system of converting electric signals into acousticbeams, irradiating the beams on the ink and jetting out the ink byutilizing the radiation pressure, and a thermal inkjet (bubble jet)system of heating the ink to form a bubble and utilizing the pressuregenerated.

The inkjet recording system includes a system of ejecting a large numberof small-volume ink droplets of a so-called photo ink having a lowconcentration, a system of improving the image quality by using aplurality of inks having substantially the same color hue but differingin the concentration, and a system using a colorless transparent ink,and the ink of the present invention can be used for all of thesesystems.

1. An inkjet recording ink comprising an aqueous medium dissolved ordispersed therein a phthalocyanine dye, wherein said phthalocyanine dyeis a water-soluble dye having an oxidation potential more positive than1.0 V (vs SCE) and the ink comprises a water-miscible organic solventhaving a vapor pressure of 2,000 Pa or less at 20° C.
 2. The inkjetrecording ink as claimed in claim 1, which comprises at least oneorganic solvent having a boiling point of 150° C. or more as thewater-miscible organic solvent.
 3. The inkjet recording ink as claimedin claim 2, wherein the at least one organic solvent having a boilingpoint of 150° C. or more is an alcohol derivative.
 4. The inkjetrecording ink as claimed in claim 1, which comprises at least oneorganic solvent having a boiling point of less than 150° C. as thewater-miscible organic solvent.
 5. The inkjet recording ink as claimedin claim 4, wherein the at least one organic solvent having a boilingpoint of less than 150° C. is an alcohol derivative.
 6. The inkjetrecording ink as claimed in claim 1, which comprises a polyhydricalcohol and/or a derivative thereof as the water-miscible organicsolvent.
 7. The inkjet recording ink as claimed in claim 6, whichcomprises a mixture of two or more members containing the polyhydricalcohol and/or a derivative thereof.
 8. The inkjet recording ink asclaimed in claim 6 or 7, which comprises the polyhydric alcohol and/or aderivative thereof at a concentration of 10 to 60 (mass/volume) %. 9.The inkjet recording ink as claimed in claim 1, which comprises anorganic solvent, in which the phthalocyanine dye has a solubility of 10(g/100 g-solvent) or more at 25° C., as the water-miscible organicsolvent.
 10. The inkjet recording ink as claimed in claim 9, whichcomprises a water-miscible organic solvent, in which the phthalocyaninedye has a solubility of 10 (g/100 g-solvent) or more at 25° C., in anamount of 10 mass % or less in the ink.
 11. The inkjet recording ink asclaimed in claim 1, which comprises an organic solvent, which is liquidat ordinary temperature and does not contain a heteroatom other than anoxygen atom, as the water-miscible organic solvent.
 12. The inkjetrecording ink as claimed in claim 11, wherein the organic solvent has aboiling point of 150° C. or more.
 13. The inkjet recording ink asclaimed in claim 11 or 12, wherein the organic solvent is an alcoholderivative and is selected from a monool, a diol and a triol.
 14. Theinkjet recording ink as claimed in claim 1, wherein the water content isfrom 40 to 80 mass % based on the ink solution.
 15. The inkjet recordingink as claimed in any one of claims 1 to 14, wherein when themonochromatic moiety printed by using a single (cyan) color of the inkso as to give a cyan reflection density of 0.9 to 1.1 in a Status Afilter is stored in an ozone environment of 5 ppm for 24 hours, a dyeresidual ratio (density after color fading/initial density×100) is 60%(preferably 80%) or more.
 16. The inkjet recording ink as claimed in anyone of claims 1 to 15, wherein after color fading with ozone under theconditions of claim 15, the amount of Cu ion flowed out into water is20% or less of all dyes.
 17. The inkjet recording ink as claimed in anyone of claims 1 to 16, wherein the phthalocyanine dye is a water-solubledye having an electron-withdrawing group at the β-position of a benzenering of said phthalocyanine.
 18. The inkjet recording ink as claimed inany one of claims 1 to 17, wherein said phthalocyanine dye is awater-soluble phthalocyanine dye produced by a process not passingthrough sulfonation of an unsubstituted phthalocyanine.
 19. The inkjetrecording ink as claimed in claims 1 to 18, wherein said phthalocyaninedye is represented by the following formula (I):

wherein X₁, X₂, X₃ and X₄ each independently represents —SO-Z, —SO₂-Z,—SO₂NR1R2, a sulfo group, —CONR1R2 or —CO₂R1; Z represents a substitutedor unsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted alkenyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,or a substituted or unsubstituted heterocyclic group, and R1 and R2 eachindependently represents a hydrogen atom, a substituted or unsubstitutedalkyl group, a substituted or unsubstituted cycloalkyl group, asubstituted or unsubstituted alkenyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,or a substituted or unsubstituted heterocyclic group, provided that whena plurality of Zs are present, these may be the same or different, Y₁,Y₂, Y₃ and Y₄ each independently represents a monovalent substituent,provided that when a plurality of X₁s, X₂s, X₃s, X₄s, Y₁s, Y₂s, Y₃s orY₄s are present, these may be the same or different, a₁ to a₄ and b₁ tob₄ represent the number of substituents X₁ to X₄ and Y₁ to Y₄,respectively, a₁ to a₄ each independently represents an integer of 0 to4 but all are not 0 at the same time, b₁ to b₄ each independentlyrepresents an integer of 0 to 4, and M represents a hydrogen atom, ametal atom or an oxide, hydroxide or halide thereof.
 20. The inkjetrecording ink as claimed in claim 19, wherein the dye represented byformula (I) is a dye represented by the following formula (II):

wherein X₁₁ to X₁₄, Y₁₁ to Y₁₈ and M₁ have the same meanings as X₁ toX₄, Y₁ to Y₄ and M in formula (I), respectively, and a₁₁ to a₁₄ eachindependently represents an integer of 1 or
 2. 21. An inkjet recordingmethod comprising using the inkjet recording ink claimed in claims 1 to20.
 22. An inkjet recording method comprising ejecting ink dropletsaccording to recording signals on an image-receiving material comprisinga support having thereon an image-receiving layer containing a whiteinorganic pigment particle, thereby recording an image on theimage-receiving material, wherein said ink droplet comprises the inkjetrecording ink claimed in claims 1 to 20.